Can´t use a4j:support when my Form is prependId="false"

[gbzao!]

Hello People!

My name is Gabriel, I am from Brazil and I have a problem with A4J.

When I set my form prependId="false", a4j:suppot don´t refresh.
But, if form prependId="true" a4j:support refresh.

Look a example:

<h:form id="form" prependId="false">

 <h:panelGrid columns="2">
 <h:inputText id="myinput" value="#{Cliente.buscaCliente}">
 <a4j:support event="onkeyup" reRender="za" />
 </h:inputText>

 <h:outputText value="#{Cliente.buscaCliente}" id="za" />
 </h:panelGrid>

</h:form>

Somebody Can Help me?

Thanks a Lot!