Revised return of vat

MY CLIENT HAS NOT FILED THE REVISED RETURN FOR THE FY 10-11.

NOW WHEN I AM REVISING THE RETURN , THE SITE IS NOT ACCEPTING THE SAME. ALL TAX DUES HAS ALREADY BEEN PAID. I WANT TO REVISE THE RETURN.

NOW, WHAT ARE THE LEGAL PENALITIES WHICH CAN BE LEIVED ON DEALER FOR NOT FILING THE REVISE RETURN. WHAT ARE REMEDIES?????

PLEASE PROVIDE ME ANSWER ALONGWITH RELEVANT SEC NO.

THANKS IN ADVANCE