Ovulation tests

Ok ladies I started testing this month again. I tested on Monday it was negative. Tuesdays test line was getting darker but still negative. Wednesdays test line was getting a little more darker but still negative. Now Thursday it was lighter line and now Friday test line is freakin lighter. What in world is going on. Last two days the test line has been lighter than Mondays and Tuesdays. I don't freaking get it. HELP... Mind you I bought ovulation tests from the Dollar Tree, wasn't sure if that's a good brand to use or not. Pink dye also.