Disappearing faint line on first response?

Kristen • 24,married and trying for my first,after a chemical pregnancy July 2015.
I took a first response today and right as the urine hit it had a very faint line but then it suddenly disappeared,I'm so confused!!! I took the digital test that came with it and it said no,but there was a line on the first test for sure. Idk if I should take it as I'm pregnant or not :(