SIP-Refer - 500 Error

I have a call that goes thru an avaya session manager to an ivr and in there you can enter a number to do a blind transfer. When the call goes back the session manager it should route to our avaya communciation manager but it does not - instead I receive a 500 Internal Server Error. I have 

 

Here is my example.

 

User calls 888-111-2222

Calls goes to the IVR where they hit an options out for a blind transfer to a number they enter

The caller enters 333-333-3333

The call routes back to the SBC with a refer-to 333-333-3333