user eixt for modifying inbound idoc (delins) not working

hi all,

Inbound IDoc DELINS.DELFOR02 is sent from customer to vendor to create forecast delivery schedule lines (VA32). E1EDP16-WMENG has the delivery quantity and it is mapped to VBEP-WMENG.

I need modify E1EDP16-WMENG accordingly (based on some business rules) and this change should also be reflected to VBEP_WMENG.

I tried to modify the idoc_data in user exits: EXIT_SAPLVED4_002, userexit_zuordnen_idocs. During debug, I can see the idoc is modified, but the final forecast delivery is not updated (VA33).

Anyone can help?

Thanks!

Regards

Hui