NIL gst annual return for FY 1718 not getting filed

We are not able to file NIL gst annual return. we do not have any transaction in FY 1718 then also portal is not allowing us to file NIL gst return. On ascertaining the issue we found that since we have cash balance as on today in our electronic cash ledger pertaining to FY 1819 or Apr 19 the portal is not allowing us to file NIL gst annual return for FY 1718.