When I Record GST Payment why do get error "You cannot create or modify transactions in the period for which tax returns are already filed."? Am posting old entries!

We have old data we have not yet processed so there is a list of GST pmts awaiting completion. They are for qtrly GST periods Jul16-Sep16, Oct16-Dec16, etc onwards so I need a workaround please so they clear off and the bank account is duly updated. Any help would be great, Thank you.