Hi Thomas Wagner and Punit Verma,
Thank you for the input. Upon testing in ECC, the system proposed the 1st payer maintained for the customer, so I think that it is being redetermined in ECC. I am going to test with newly created customer and inform you with the result.
2014-08-12: there is a partner function code mapping which was not set for payer ( PY = RG )
reference for this mapping was taken from ecc table TPAUM
Tuwuh SW