primefaces update attribute not working - jsf

Question

Whenever I run the following code on Home.xhtml page, I get the following exception. I try to call the contents of panel with id = items but without success. It says that compiler cannot find the component with items identifier.
1)part of Home.xhtml
<h:form>
<p:commandButton type="submit" value="Speak Out" action="#{statusBean.save}" ajax="true" styleClass="buttonstyle" update="items"/>
</h:form>
<p:panel id="items">
//content
</p:panel>
2)Exception
Mar 12, 2013 1:38:04 AM com.sun.faces.application.view.FaceletViewHandlingStrategy handleRenderException
SEVERE: Error Rendering View[/Home.xhtml]
javax.faces.FacesException: Cannot find component with identifier "items" in view.
at org.primefaces.util.ComponentUtils.findClientIds(ComponentUtils.java:249)
at org.primefaces.renderkit.CoreRenderer.buildAjaxRequest(CoreRenderer.java:222)
at org.primefaces.component.commandbutton.CommandButtonRenderer.encodeMarkup(CommandButtonRenderer.java:81)
at org.primefaces.component.commandbutton.CommandButtonRenderer.encodeEnd(CommandButtonRenderer.java:53)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:879)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1650)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:164)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:849)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:300)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:181)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:125)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:849)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1643)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1646)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1646)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:389)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:127)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:117)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:135)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:309)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
Mar 12, 2013 1:38:04 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [Faces Servlet] in context with path [/FreeBird_v.6] threw exception [Cannot find component with identifier "items" in view.] with root cause
javax.faces.FacesException: Cannot find component with identifier "items" in view.
at org.primefaces.util.ComponentUtils.findClientIds(ComponentUtils.java:249)
at org.primefaces.renderkit.CoreRenderer.buildAjaxRequest(CoreRenderer.java:222)
at org.primefaces.component.commandbutton.CommandButtonRenderer.encodeMarkup(CommandButtonRenderer.java:81)
at org.primefaces.component.commandbutton.CommandButtonRenderer.encodeEnd(CommandButtonRenderer.java:53)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:879)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1650)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:164)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:849)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:300)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:181)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:125)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:849)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1643)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1646)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1646)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:389)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:127)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:117)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:135)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:309)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)

Answer 1

Okey, shortly you should try :items, because it's outside the component tree. And for more details of using ajax behavior of primefaces you can check the examples in showcase from here. In addition you can use firebug in this case to observe your components.
EDIT:
After BalusC's warning, it's correct that your problem lies on not due to the it's not inside the same component tree, because it's not in the same NamingContainer.
Standard components like h: form , f: subview and h: dataTable are naming containers. Most sets of components possess in some naming containers, so in your case it's outside of the tag for that reason :items will be correct way to refer it.
Please refer to these posts help you understand the topic nicely:
Jsf How to create a Naming Container
Naming Container and Jsf