Unable to offset liabilityin gstr3b

Trying to file GSTR3b for December 17. After entering payment details, duly taking care to adhere to offset rules, when I click" OFFSET LIABILTY" a sucess page should appear asking me to click 'OK". But it is not appearing. Off set is not happening. "Paymnet of Tax" tile, still shows tax liability. Status of the return appearing as " SUBMITTED". Help please.