Did you elect to NOT carry the NOL back in the prior year? Without the election to waive the carryback, you would need to carry any NOL back 5 years. https://www.irs.gov/pub/irs-pdf/p536.pdf 

If there truly is a remaining NOL, you would need to enter the carryovers by year in Income > Federal Net Operating Loss and also for the state (which is likely a different number)