Hi Ranu,
Thanks for your reply. I have gon through the document. I have done the same thing which you have mentioned in document and above as well.
Let me explain you what I have done in order to populate BELNR field in DMe file.
As mentioned I have copied the above fm template where extension is copied. I have written the below code. Please correct me If I am wrong.
if ( i_extension-node-node_id = 'N_1035514390' ).
CLEAR: lv_belnr,lv_ovbln.
lv_ovbln = ls_item-fpayh-ovbln.
lv_bukrs = ls_item-fpayh-bukrs.
lv_gjahr = ls_item-fpayh-gjahr.
lv_buzei = ls_item-fpayh-buzei.