I have the following page

<h:form prependId="false" >

                 <rich:dataTable value="#{controller.getFields()}" var="field" >

                     <rich:column>

                         <f:facet name="header">Nome</f:facet>

                        <h:column>#{field.nome}</h:column>

                    </rich:column>                   

                 </rich:dataTable>

                 <a4j:commandButton value="Add" execute="@form" render="popupPanel" action="#{assetTypeController.setViewPopup(true)}" immediate="true" >

<a4j:outputPanel id="popupPanel" >

                <rich:popupPanel id="popup"  resizeable="true" show="true"

                    onmaskclick="#{rich:component('popup')}.hide()" rendered="#{assetTypeController.viewPopup}">

                        <f:facet name="header">

                            <h:outputText value="Simple popup panel" />

                        </f:facet>

                        <f:facet name="controls">

                            <a4j:commandLink action="#{assetTypeController.setViewAddFieldPopup(false)}"

                                onclick="#{rich:component('addFieldPopup')}.hide(); return false;"  >X</a4j:commandLink>

                        </f:facet>

                        <p>You can also check and trigger events if the use clicks

                            outside of the panel.</p>

                        <p>In this example clicking outside closes the panel.</p>

                </rich:popupPanel>

            </a4j:outputPanel>

</h:form>

when I run the command "Add" the page recall the method controller.getFields(), why?

thanks