Faint line but positive digital...

Alissa • Pregnant with my rainbow baby! Due 2/23/2016!
How accurate are digital pregnancy tests? I got a faint line from a dollar store test which are notorious for evap lines. I got a Rite Aid digital test which says I'm pregnant. I also took a dollar store test yesterday and it was negative. My period is 4 days late. I just want to know how trustworthy digital tests are.