advice?

So I would like some input on something. This morning I took a pregnancy test (clinical guard) that had a faint line(first pee of the day) then later on in the day I went to the store and got a first response test and wanted to confirm the results. this was negative. Should I assume there was an error with my first test or should I try again in a few days with another test? What do you think?  I am 7 DPO and 7 days from AF. Is it still too early?