How exactly do you call the bpel process?
How do you show the pop-up?
Some code would help to understand what you have done so far.
I presume , you have an action listener on your submit which calls Bpel activity .
Instead of using show popup behaviour , write the code in action listener to launch popup programatically.
RichPopup.PopupHints a = new RichPopup.PopupHints();
where receivedFlagPopUp is the binding of appropriate popup in backingbean.
Hope it helps.