Hi Amar,
In SAP standard system the field REGUH-BKREF is filled from
vendor/customer master record (tr. FK03 / FD03 ->
tab 'Payment transactions' ->
field 'Reference details' LFBK-BKREF / KNBK-BKREF).
1) Please, make sure that in customer master record field
'Reference details' KNBK-BKREF is filled correctly.
2) Create a new payment proposal and check in tr. SE16
the field REGUH-BKREF.
Also, have in mind that for this works, the below customizing should be set in the system:
tr. FBZP -> Payment method in country:
Country: XX
Payment method: X
frame 'Required master record specifications' ->
x Bank details
x Account number required
x Collection authorization
Regards,
Cristiano