1 : unbounded messages flow

I'm mapping a flat structure into several BAPIs. However, only one BAPI seems to get sent. I have 1 to unbounded in the interface mapping.

ex:

<b>Source</b>
Messages 1:1
  Message1 1:1
    ExportOrder_MT 1:1 
      Data

<b>Target</b>
Messages 1:1
  Message1 1:1
    Y_BAPI_SALESORDER_CHANGE 1:unbounded
      Data

Though I produce multiple BAPIs in the PE/mapping section, I'm only sending one BAPI over to SAP system. Not sure what's happening. ANy ideas?

Thank you, Pam