energy tax credit

From what I read congress extended the energy tax credit for windows and door to cover 2018 and 2019.  When I looked at my 2018 form 5695 the $525 expense for the door never yielded the 10% credit.  If I had a carryover from 2017 my refund increased. Is this situation correct that I was not entitled  to the credit in 2018? I have a window replacement for 2019 that I'm also going to try to get the credit for.