Primefaces update strange behaviour - jsf

Question

i have a strange behaviour on Primefaces update :
I have i page with a panel grid with several output text and a dataTable with several rows. If I modify a row, the datatable update correctly, but if I insert a new row or delete a row it doesn't update. The page code is the following:
<ui:composition>
<p:dialog id="composizioneDlg" widgetVar="ComposizioneDialog" modal="true" resizable="false" appendTo="#(body)" header="#{bundle.ListDescImmTitle}">
<h:form id="composizioneListForm">
<p:panelGrid columns="10" rendered="#{immobiliController.selected != null}">
<h:outputText value="#{bundle.ViewImmobiliLabel_categoria}"/>
<h:outputText value="#{immobiliController.selected.categoria.descrizione}"
-------SEVERAL OUTPUTS---------------------------------
</p:panelGrid>
<p:panel header="#{bundle.ListDescImmTitle}">
<p:dataTable id="datalistComp" value="#{descImmController.composizione}" var="item" >
-----SEVERAL OPTIONS OF DATA TABLE-------------------
<p:ajax event="rowSelect" update="createButton viewButton editButton deleteButton"/>
<p:ajax event="rowUnselect" update="createButton viewButton editButton deleteButton"/>
<p:column>
<f:facet name="header">
<h:outputText value="#{bundle.ListDescImmTitle_stato}"/>
</f:facet>
<h:outputText value="#{item.stato}"/>
</p:column>
<p:column>
<f:facet name="header">
<h:outputText value="#{bundle.ListDescImmTitle_categoria}"/>
</f:facet>
<h:outputText value="#{item.categoria}"/>
</p:column>
<p:column>
<f:facet name="header">
<h:outputText value="#{bundle.ListDescImmTitle_descrizione}"/>
</f:facet>
<h:outputText value="#{item.descrizione}"/>
</p:column>
<p:column>
<f:facet name="header">
<h:outputText value="#{bundle.ListDescImmTitle_mq}"/>
</f:facet>
<h:outputText value="#{item.mq}"/>
</p:column>
<f:facet name="footer">
<p:commandButton id="createButton" icon="ui-icon-plus" value="#{bundle.Create}" actionListener="#{descImmController.prepareCreate}" update=":DescImmCreateForm" oncomplete="PF('DescImmCreateDialog').show()"/>
<p:commandButton id="editButton" icon="ui-icon-pencil" value="#{bundle.Edit}" update=":DescImmEditForm" oncomplete="PF('DescImmEditDialog').show()" disabled="#{empty descImmController.selected}"/>
<p:commandButton id="deleteButton" icon="ui-icon-trash" value="#{bundle.Delete}" actionListener="#{descImmController.destroy}" update=":composizioneListForm:datalistComp, :growl" disabled="#{empty descImmController.selected}"/>
</f:facet>
</p:dataTable>
</p:panel>
</h:form>
</p:dialog>
</ui:composition>
The editButton code is this ( and it works ):
<ui:composition>
<p:dialog id="DescImmEditDlg" widgetVar="DescImmEditDialog" modal="true" resizable="false" appendTo="#(body)" header="#{bundle.EditDescImmTitle}">
<h:form id="DescImmEditForm">
<h:panelGroup id="display">
<p:panelGrid columns="2" rendered="#{descImmController.selected != null}">
<p:outputLabel value="#{bundle.EditDescImmLabel_stato}" for="stato" />
<p:inputText id="stato" value="#{descImmController.selected.stato}" title="#{bundle.EditDescImmTitle_stato}" />
<p:outputLabel value="#{bundle.EditDescImmLabel_descrizione}" for="descrizione" />
<p:inputText id="descrizione" value="#{descImmController.selected.descrizione}" title="#{bundle.EditDescImmTitle_descrizione}" />
<p:outputLabel value="#{bundle.EditDescImmLabel_mq}" for="mq" />
<p:inputText id="mq" value="#{descImmController.selected.mq}" title="#{bundle.EditDescImmTitle_mq}" />
</p:panelGrid>
<p:commandButton actionListener="#{descImmController.update}" value="#{bundle.Save}" update="display, :composizioneListForm:datalistComp, :growl" oncomplete="handleSubmit(args, 'DescImmEditDialog');"/>
<p:commandButton value="#{bundle.Cancel}" onclick="DescImmEditDialog.hide()"/>
</h:panelGroup>
</h:form>
</p:dialog>
</ui:composition>
This is the code of createButton ( not update instead of editButton ) :
<ui:composition>
<p:dialog id="DescImmCreateDlg" widgetVar="DescImmCreateDialog" modal="true" resizable="false" appendTo="#(body)" header="#{bundle.CreateDescImmTitle}">
<h:form id="DescImmCreateForm">
<h:panelGroup id="display">
<p:panelGrid columns="2" rendered="#{descImmController.selected != null}">
<p:outputLabel value="#{bundle.CreateDescImmLabel_descrizione}" for="descrizione" />
<p:inputText id="descrizione" value="#{descImmController.selected.descrizione}" title="#{bundle.CreateDescImmTitle_descrizione}" />
<p:outputLabel value="#{bundle.CreateDescImmLabel_mq}" for="mq" />
<p:inputText id="mq" value="#{descImmController.selected.mq}" title="#{bundle.CreateDescImmTitle_mq}" />
</p:panelGrid>
<p:commandButton actionListener="#{descImmController.create}" value="#{bundle.Save}" update="display, :composizioneListForm:datalistComp, :growl" oncomplete="handleSubmit(args,'DescImmCreateDialog');"/>
<p:commandButton value="#{bundle.Cancel}" onclick="DescImmCreateDialog.hide()"/>
</h:panelGroup>
</h:form>
</p:dialog>
</ui:composition>
Where is my fault on call update="" in deleteButton and in createButton ????

Answer 1

After rewrite the code from the beginning ( but with the same code ) all goes well. Now It works