What is short name of program which you ran (get it from log file ) ?
XXRAXINV_SEL_OU is the program short name which is the custom program of seeded RAXINV_SEL program.
As this is a custom program, confirm if the xml is getting generated correctly.
XML file generated should be openable in browser.
Check is OPP manager is getting called in the log file.
No xml is not generated and view xml is disabled.
No OPP reference is not available in main and xml publisher request in printing credit memo too.
Credit memo is not printing for this alone.