fnd_transaction.synchronous Sometimes It Works, Sometimes It Does Not for RCVTPO

@po_header[

I am using PLSQL-SPEC to run RSpec tests and would like to use fnd_transaction.synchronous to invoke the receiving transaction processor.  Sometimes this works and sometimes it does not.  I think the wind outside plays a factor.    Does anyone know why this would be the case?  The receiving manager has 5 threads and sleeps every 60 seconds.

Here is the call:

plsql.fnd_transaction.synchronous(:timeout=>300,

        :outcome=>outcome,

        :message=>message,

        :application=>'PO',

        :program=>'RCVTPO',

        :arg_1=>'ONLINE',

        :arg_2=>'96',

        :arg_3=>@po_header[:org_id].to_s)

Thank you