Hello,
Attribute REQUISITIONER is not intended to support an F4 help in PPOMA_BBP. For this reason you are not seeing any result.
You have to enter manually the entries: either 'O xxxxx..' (xxxx...=org. unit no.) or USyyyy...' (yyyy...=username).
As in PPOMA_BBP, when updating REQUISITIONER attribute, you should maintain it manually.
Regards,
Ricardo