positive yesterday, nothing this morning?

I took a test yesterday afternoon and saw a faint pink line within the 3 minute timeframe. So exciting! I decided to take the same type of test this morning as soon as I got up trying to get a more concentrated amount of urine on the stick. The line (if there was any) was much lighter than the previous test. Such disappointment! Anyone have anything like this before? 
1st one. 
2nd one.