RMA Receipt email

I am trying to do a BPM email notifcation if a part on an RMA Receipt is on hold. The part num is on the receipt and I tried doing a BPM hold and attach the part object to the RMA receipt but that does not seem to work. I am able to stop order entry using a BPM hold with this part but I can not even get a message to pop up on the receipt, let alone an email. Any suggestions? Thank you.