When I set RECEIPT triggers I check the "Once on next occurance" box. Other than the fact that occurrence is misspelled :-p, the triggers don't go off when the PO item is received. If the box is not checked they work fine.
 
BTW, my expectation for this feature (the check box) would be that it sends the trigger and deletes itself from the list of triggers once it has been acknowledged/dismissed. I would also expect to still find the event listed if I look on the calendar for the day it was triggered.
 
In case I have not said it clearly before, I LOVE the triggers! The interface needs some tweaks (like entering EFP WO #s, and putting Save into the tab order), but it is a great feature that is helping us to automate WO processes, keep track of MRP issues, see late POs, see expiring product, and has great future potential, as well. Thank you!