Thank You Sir,
Below is the code of my header....
wa_header-obj_type = 'BKPFF'.
wa_header-obj_key = '$'.
call function 'OWN_LOGICAL_SYSTEM_GET'
importing
own_logical_system = wa_header-obj_sys
exceptions
own_logical_system_not_defined = 1
others = 2.
wa_header-bus_act = 'RMRP'.
wa_header-comp_code = wa_final-bukrs.
wa_header-username = sy-uname.
wa_header-header_txt = 'Debit Note Auto Post'.
wa_header-doc_date = wa_final-bldat.
wa_header-pstng_date = wa_final-budat.
wa_header-ref_doc_no = wa_final-dnumber.
wa_header-doc_type = 'KG'.
Regards,
Hardik B