Had a positive and neg... confused

AF due sunday. Wednesday night I took a FRER test, immediately I saw faint line and so did my husband. The next morning I took a FRER digital and it said no. (oops, i opened it to look and no line). Why would that be? I really do think I am pregnant, and I have been twice before so I know what I’m looking for. My husband won’t let me take another test till Wednesday lol. It could’ve just be it wasn’t enough for the digital to pick up???