RM06BZ10 is not behaving same as ME57 in perspective of source determination?

Hello

ME57 (under lying program is RM06BZ00) is working fine and getting correct source, well, but we expected the program RM06BZ10 also works same as ME57, but not in perspective of source detrmination, pls. let me know how the source is determined in program RM06BZ10?

Thank you