dollar store accurate?

I took a test to prove my friend wrong and Bc I don't know how I could be. We've been trying for over 4 years.  I did the dollar store test middle of afternoon to prove I wasn't.  Looked at about 5 mins didn't see anything and continued talking at about 10-15 mins I went to throw it away and saw the top.  A few hrs later I used the same pee as earlier on a FRER and it was negative. I don't see anything on the bottom one. 
Can older pee affect anything and are dollar stores known for false positives?