Why won't TurboTax 2017 use my old .tax2017 file information to Amend my 2017 Federal return?

I am trying to amend my 2017 taxes. I have TurboTax 2017 Home & Business installed and my old .tax2017 file from when I last filed. When I open that file it won't let me begin Amending it anywhere - Am I missing something? It will let me start from scratch if I open a new file and click "Amend a return" but it doesn't seem to import anything in that case, and wants me to enter in all my information from scratch. Help!