RosettaNet process on the fulfiller side not starting up..

I am trying to implement the Service Entitlement i.e RosettaNet 6C1 in IS 6.1 SP1. I have configured the process models (2 - Action PIP Initator and Responder models).
When i am running the process model , the initiator model waits at step for Acknowledgement receipt from the fuilfiller. The fulfiller process is not starting up. I cannot see any error in any of the logs. When i move on to the Activity log in the TN. i can see that the document is persisted and the system recognizes the document and i can also see the preable Header, Service Content and Service Header. Everything seems to be fine but not working. Please help me out

On your receiver model ensure that you have assigned the correct doctype to the very first step in the model. If your document is recognized and persisted in TN it means that the transition from TN to the PRT is causing some issues and checking the input subscription to the very first step in the model would be a good place to start!
I hope this helps!