Ovualtion Test line?

Ok so I bought cheap internet ovualtion tests. I ended my period 2 days ago And I figured id try one out. It was only one line. There was no second line at all. Not even really faint. So my question is are you always suppose to have a second very faint line when you are not ovulating? I read online that there is always suppose to be Lh in your system but around ovualtion it's strong which causes the dark second line. I am alittle confused. Please help ? thanks!