FreeMarker template error!

Expression article is undefined on line 7, column 18 in WEB-INF/tiles/tiles/message/article/main-column.ftl.
The problematic instruction:
----------
==> ${article.title} [on line 7, column 16 in WEB-INF/tiles/tiles/message/article/main-column.ftl]
----------

Java backtrace for programmers:
----------
freemarker.core.InvalidReferenceException: Expression article is undefined on line 7, column 18 in WEB-INF/tiles/tiles/message/article/main-column.ftl.
	at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
	at freemarker.core.TemplateObject.invalidTypeException(TemplateObject.java:135)
	at freemarker.core.Dot._getAsTemplateModel(Dot.java:78)
	at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
	at freemarker.core.Expression.getStringValue(Expression.java:93)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.MixedContent.accept(MixedContent.java:92)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.Environment.process(Environment.java:199)
	at freemarker.template.Template.process(Template.java:237)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:452)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:391)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
	at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427)
	at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:875)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:723)
	at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:679)
	at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:594)
	at freemarker.ext.jsp.FreeMarkerPageContext.include(FreeMarkerPageContext.java:407)
	at org.apache.tiles.jsp.context.JspTilesRequestContext.include(JspTilesRequestContext.java:103)
	at org.apache.tiles.jsp.context.JspTilesRequestContext.dispatch(JspTilesRequestContext.java:96)
	at org.apache.tiles.renderer.impl.TemplateAttributeRenderer.write(TemplateAttributeRenderer.java:44)
	at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
	at org.apache.tiles.renderer.impl.ChainedDelegateAttributeRenderer.write(ChainedDelegateAttributeRenderer.java:76)
	at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:670)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:336)
	at org.apache.tiles.template.InsertAttributeModel.renderAttribute(InsertAttributeModel.java:210)
	at org.apache.tiles.template.InsertAttributeModel.end(InsertAttributeModel.java:126)
	at org.apache.tiles.jsp.taglib.InsertAttributeTag.doTag(InsertAttributeTag.java:311)
	at freemarker.ext.jsp.SimpleTagDirectiveModel.execute(SimpleTagDirectiveModel.java:76)
	at freemarker.core.Environment.visit(Environment.java:274)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:126)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.MixedContent.accept(MixedContent.java:92)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.Environment.process(Environment.java:199)
	at freemarker.template.Template.process(Template.java:237)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:452)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:391)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
	at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427)
	at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:875)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:723)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:558)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:490)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:382)
	at org.apache.tiles.servlet.context.ServletTilesRequestContext.forward(ServletTilesRequestContext.java:241)
	at org.apache.tiles.servlet.context.ServletTilesRequestContext.dispatch(ServletTilesRequestContext.java:222)
	at org.apache.tiles.renderer.impl.TemplateAttributeRenderer.write(TemplateAttributeRenderer.java:44)
	at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:670)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:690)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:644)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:627)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:321)
	at org.springframework.web.servlet.view.tiles2.TilesView.renderMergedOutputModel(TilesView.java:124)
	at com.ppc.webcore.tiles.ExtTilesView.renderMergedOutputModel(ExtTilesView.java:48)
	at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:262)
	at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1157)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:927)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
	at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:333)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:311)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:116)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:101)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:182)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.access.channel.ChannelProcessingFilter.doFilter(ChannelProcessingFilter.java:144)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:173)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:246)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:313)
	at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:287)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:218)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
	at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:94)
	at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:98)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:222)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1096)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:166)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1096)
	at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:288)
	at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.invokeAdapter(DefaultProcessorTask.java:647)
	at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.doProcess(DefaultProcessorTask.java:579)
	at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.process(DefaultProcessorTask.java:831)
	at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.executeProcessorTask(DefaultReadTask.java:341)
	at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:263)
	at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:214)
	at com.sun.enterprise.web.portunif.PortUnificationPipeline$PUTask.doTask(PortUnificationPipeline.java:380)
	at com.sun.enterprise.web.connector.grizzly.TaskBase.run(TaskBase.java:265)
	at com.sun.enterprise.web.connector.grizzly.ssl.SSLWorkerThread.run(SSLWorkerThread.java:106)

FreeMarker template error!

org.apache.tiles.util.TilesIOException: JSPException including path '/WEB-INF/tiles/tiles/message/article/main-column.ftl'.
The problematic instruction:
----------
==> user-directive tiles.insertAttribute [on line 36, column 7 in WEB-INF/tiles/layouts/two-column-opt.ftl]
----------

Java backtrace for programmers:
----------
freemarker.template.TemplateModelException: org.apache.tiles.util.TilesIOException: JSPException including path '/WEB-INF/tiles/tiles/message/article/main-column.ftl'.
	at freemarker.ext.jsp.SimpleTagDirectiveModel.execute(SimpleTagDirectiveModel.java:90)
	at freemarker.core.Environment.visit(Environment.java:274)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:126)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.MixedContent.accept(MixedContent.java:92)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.Environment.process(Environment.java:199)
	at freemarker.template.Template.process(Template.java:237)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:452)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:391)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
	at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427)
	at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:875)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:723)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:558)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:490)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:382)
	at org.apache.tiles.servlet.context.ServletTilesRequestContext.forward(ServletTilesRequestContext.java:241)
	at org.apache.tiles.servlet.context.ServletTilesRequestContext.dispatch(ServletTilesRequestContext.java:222)
	at org.apache.tiles.renderer.impl.TemplateAttributeRenderer.write(TemplateAttributeRenderer.java:44)
	at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:670)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:690)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:644)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:627)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:321)
	at org.springframework.web.servlet.view.tiles2.TilesView.renderMergedOutputModel(TilesView.java:124)
	at com.ppc.webcore.tiles.ExtTilesView.renderMergedOutputModel(ExtTilesView.java:48)
	at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:262)
	at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1157)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:927)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
	at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:333)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:311)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:116)
	at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:101)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:182)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.access.channel.ChannelProcessingFilter.doFilter(ChannelProcessingFilter.java:144)
	at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:323)
	at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:173)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:246)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:313)
	at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:287)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:218)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
	at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:94)
	at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:98)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:222)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1096)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:166)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:648)
	at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:593)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:587)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:1096)
	at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:288)
	at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.invokeAdapter(DefaultProcessorTask.java:647)
	at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.doProcess(DefaultProcessorTask.java:579)
	at com.sun.enterprise.web.connector.grizzly.DefaultProcessorTask.process(DefaultProcessorTask.java:831)
	at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.executeProcessorTask(DefaultReadTask.java:341)
	at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:263)
	at com.sun.enterprise.web.connector.grizzly.DefaultReadTask.doTask(DefaultReadTask.java:214)
	at com.sun.enterprise.web.portunif.PortUnificationPipeline$PUTask.doTask(PortUnificationPipeline.java:380)
	at com.sun.enterprise.web.connector.grizzly.TaskBase.run(TaskBase.java:265)
	at com.sun.enterprise.web.connector.grizzly.ssl.SSLWorkerThread.run(SSLWorkerThread.java:106)
Caused by: org.apache.tiles.util.TilesIOException: JSPException including path '/WEB-INF/tiles/tiles/message/article/main-column.ftl'.
	at org.apache.tiles.servlet.context.ServletUtil.wrapServletException(ServletUtil.java:241)
	at org.apache.tiles.jsp.context.JspTilesRequestContext.include(JspTilesRequestContext.java:105)
	at org.apache.tiles.jsp.context.JspTilesRequestContext.dispatch(JspTilesRequestContext.java:96)
	at org.apache.tiles.renderer.impl.TemplateAttributeRenderer.write(TemplateAttributeRenderer.java:44)
	at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
	at org.apache.tiles.renderer.impl.ChainedDelegateAttributeRenderer.write(ChainedDelegateAttributeRenderer.java:76)
	at org.apache.tiles.renderer.impl.AbstractBaseAttributeRenderer.render(AbstractBaseAttributeRenderer.java:106)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:670)
	at org.apache.tiles.impl.BasicTilesContainer.render(BasicTilesContainer.java:336)
	at org.apache.tiles.template.InsertAttributeModel.renderAttribute(InsertAttributeModel.java:210)
	at org.apache.tiles.template.InsertAttributeModel.end(InsertAttributeModel.java:126)
	at org.apache.tiles.jsp.taglib.InsertAttributeTag.doTag(InsertAttributeTag.java:311)
	at freemarker.ext.jsp.SimpleTagDirectiveModel.execute(SimpleTagDirectiveModel.java:76)
	... 95 more
Caused by: freemarker.core.InvalidReferenceException: Expression article is undefined on line 7, column 18 in WEB-INF/tiles/tiles/message/article/main-column.ftl.
	at freemarker.core.TemplateObject.assertNonNull(TemplateObject.java:125)
	at freemarker.core.TemplateObject.invalidTypeException(TemplateObject.java:135)
	at freemarker.core.Dot._getAsTemplateModel(Dot.java:78)
	at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
	at freemarker.core.Expression.getStringValue(Expression.java:93)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.MixedContent.accept(MixedContent.java:92)
	at freemarker.core.Environment.visit(Environment.java:221)
	at freemarker.core.Environment.process(Environment.java:199)
	at freemarker.template.Template.process(Template.java:237)
	at freemarker.ext.servlet.FreemarkerServlet.process(FreemarkerServlet.java:452)
	at freemarker.ext.servlet.FreemarkerServlet.doGet(FreemarkerServlet.java:391)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
	at org.apache.catalina.core.ApplicationFilterChain.servletService(ApplicationFilterChain.java:427)
	at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:875)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:723)
	at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:679)
	at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:594)
	at freemarker.ext.jsp.FreeMarkerPageContext.include(FreeMarkerPageContext.java:407)
	at org.apache.tiles.jsp.context.JspTilesRequestContext.include(JspTilesRequestContext.java:103)
	... 106 more