I need to show a list inside of a modal panel. But list doesn't show up in first opening. After I push a button inside of the modal panel it shows up. What may be the reason of this?

This is the code for the list located in ModalPanel

<rich:panel id="planitem" >
<a4j:region>
<rich:dataTable id="planitemList" var="di"
value="#{declarationHome.planitem}">
<rich:column>
<f:facet name="header">Amount</f:facet>
 #{di.amount}
</rich:column>
</rich:dataTable>
</a4j:region>
</rich:panel>

this is the code which calls modalpane

<a4j:commandLink id="addSuperCategory" value="Dağıtım"
action="#{declarationHome.selectOrderItem}" rerender="categoryForm,planitem,planitemList"
oncomplete="Richfaces.showModalPanel('distModalPanel')">
<f:param name="orderitemId" value="#{oi.id}" />

list is assigned in selectOrderItem method which is called at the same time with modalpane