No document number generated in BAPI_REPMANCONF1_CREATE_MTS

hie gurus i, experiencing a problem with BAPI_REPMANCONF1_CREATE_MTS , its not generating backflush doc number

e.g 4900001027 . in transaction MF12 , its just outputing header info (e.g plant . production version , storage location , unit , quantity ) , table BLPK is populating but not BLPP is not .