? is the meaning of this err. message


(Guest)
8 Challan C5 - PAN Correction Last Date of 'Bank Challan No / Transfer Voucher No' 16 - T-FV-3037 Invalid 'Last Date of Bank Challan' / 'Transfer Voucher' / 'Form 24G'.

This message I got while validating RPU on correcting some PAN Nos.on downloading the file for correction.  Please note that I did not make any changes in any other field except PAN Nos.

WHY I got his message. what does this indicate.