Hi Ravi ,
RFEKA400 program reads segment 25 and identifies the house bank account in the format as follows
Bank ID/Account ID such as :25:60070080/1709111 or :25:XXFCDEKL/1709111 (or IBAN).
Your error is triggered because segment 25 only has account ID. Usually where banks are not willing to change the information in this segment of MT940, you would use alternative account number in FI12.
Regards
Taro