- Can you check if Unrestricted JCE is installed on your server?
- The fact that the partner is accepting a non -signed message tells me that it could also be the case that the Partner expects a Non-Signed Message and if rejecting the message from PI..
- Also, maybe installing a XPI_INSPECTOR run of this could help see, the exact point it fails,i.e, before sending to partner or after..
Regards
Bhavesh