Hi VINAYAK CHAVAN...
Try This, Add the below code in the Transaction notification.
change U_UDF with your original UDF Field....
If @transaction_type ( 'A','U') and @object_type = '15'
Begin
If exists
(Select Docentry From DLN1 Where DocEntry = @list_of_cols_val_tab_del
and VatGroup='CST2%' and isnull(U_UDF ,' ')=' ' )
Select @error=10,
@error_message='You should fill you UDF'
End
Regards
Kennedy