PF Poll doesn't update into modal dialog

Question

I'm using primefaces poll to dispaly incrementing counter value into a modal dialog. But it doesn't work. I placed the same code in the main form and it worked very well. But I need to display counter value into the modal dialog.

<p:dialog  id="dlgPoll" widgetVar="blockUIWidget1" header="Hitonclick"  modal="true"
   resizable="false" closable="false"  >  
<h:form>
   <h:outputText id="txt_count" value="Extracting is in progress. Please wait...  
   #{mailMB.count}" /> 
   <p:poll listener="#{mailMB.increment}" interval="1" update="txt_count"  > 
   </p:poll>
</h:form>
</:p:dialog>