BPM-Synch to Synch Interface Communication

Question

Hello All  -
My scenario is Outbound Synchronous Interface (IfOut_Synch,from JMS Adapter))->BPM->Inbound Synchronous Ingterface(PO CHNAGE BAPI).
In BPM, I want to have Receive->Transformation(Message Mapping to BAPI)->Send steps to achieve this scenario.
I created :
Interface -
1. IfOut_Synch(Synchronous Interface to get the data from JMS Adapter)
2. AbstractRequest_Asynch(Message type=PORequest from JMS)
3. AbstractResponse_Asynch(Message type=POResponse to JMS)
4. AbstractRequest_Synch (Message Type=Exactly same as IfOutSynch)
5. AbstractBAPI_Synch(Message Type=BAPI request &  BAPI Response)
Interface Mapping -
AbstractRequest_Synch <=> BAPI_PO_CHANGE
In BPM:
Containers- 
MsgOut(type AbstractRequest_Asynch)
MsgIn (type  AbstractResponse_Asynch)
Receive step-
Message=MsgOut, Mode=opens S/A Bridge, Synchronous Interface=AbstractRequest_Synch
Transformation Step-
Inertface Mapping=As defined above, Source message=MsgOut,Target Message=MsgIn
Send Step-
Mode=Close S/A bridge, Message=MsgIn, Opened by=Receive step.
I am getting Errors in Transformation Step, EXPRESSION MUST RETURN THE INTERFACE TYPE <Source message> AND EXPRESSION MUST RETURN THE INTERFACE TYPE <Target message> .
Pls advice, Anybody ??
I suspect this is because the Container is the Asynchronous Type but assigned to Synchronous Interface. While, Contained does not accept the Synchronous Type of Abstract Interface.
Thanx in Adavce....

Answer 1

I'm not sure Block in (par)foreach mode is the best option for multiple synchronous calls.
Anyway, you can always add a exception branch within your block and catch the exception from the send step. If you just want the next steps to continue, you can just do nothing in the exception branch (or maybe log an error message).
Regards,
Henrique.