Digital or other OPK?

Angela • 4 years of hoping & finally enjoying my miracle 💝
I've been using a Walgreens digital OPK but the first 4 tests I've done come out negative and I've tested on all my most fertile days even yesterday my most fertile....am I just missing it or is it just that hard to pinpoint...I notice those other OPK sticks where u can kinda see a line...would those be easier?