3591035 - B2B EDI Separator does not process messages

In a B2B scenario an EDI Separator Sender Channel is used to receive the EDI Files. During the message process below exception occurs:
com.sap.aii.af.lib.mp.module.ModuleException: Can't dispatch the message for  sender channel for Edifact message with Message type xxx, Message version number x, Message release number...
Current channel Edifact channel xxx waiting for messages matching with Message type xxx, Message version number D, Message release number
com.sap.aii.af.lib.mp.module.ModuleException: Cannot get Message InputStream: while trying to invoke the method com.sap.engine.interfaces.messaging.api.Message.getMessageKey() of a null object loaded from a local variable at slot 10    

• SAP NetWeaver
• SAP Process Integration
• Process Orchestration

Process Orchestration 7.50, PI 7.50, PO 7.50, EdifactConverterModule, B2B, AS2, Splitter   , KBA , BC-XI-CON-B2B-ESP , Electronic Data Interchange Separator , BC-XI-CON-B2B-AS2 , Applicability Statement Protocol Adapter , Problem