Hi,
1.Put breakpoint in CRM_ORDER_MAINTAIN function module.
2.Go to CRMD_ORDER transaction and try to update billing plan status and save.
3.Breakpoint will trigger. then check the parameters which are passing?
Eg. CT_Input_fields or ET_partner or ET_orderadm_h.
4.In your se38 program use CRM_ORDER_MAINTAIN fm and pass the parameters which are found in Debugging.