Schedule Agreement User Exit

Hi friends..

I'm trying to create schedule lines as and when user enters the schedule aggrement item.. everything is getting updated but the not able to see the confirmed quantity getting updated. and for this i called the routine FCODE_BVFP but then also its not performing anything. can someone sueggest me if i'm doing anythig wrong....

here is my code

xvbep-etenr = xvbep-etenr + 1.

xvbep-wmeng = li_slines-req_qty.

xvbep-edatu = li_slines-req_date.

xvbep-prgrs = '1'.

APPEND xvbep.

CLEAR xvbep.

PERFORM FCODE_BVFP.