Errors on Digital test

Morgan • Momma to 💙♥️ Twins 8/19

I took two digital pregnancy tests and BOTH came back invalid. Haven't had my period since January, but that's not strange for me since I don't ovulate on my own normally. I did 18mo of infertility to conceive my twins, so I KNOW how to pee on a stick 😂 Has anyone had this happen before? Do I need to go with the plain old line ones or is there a special way to use a digital?