Ovulation tests getting lighter?

Is it normal? I thought it was suppose to get darker as you approach ovulation predicted date. I’ve been taking the tests in the morning and each passing day it seems to be getting lighter and lighter. Idk. I’m worried about missing my ovulation. I did the 11 days after the start of my period and I roughly have a 28 week cycle. It’s predicted I will ovulate in 2 days but I feel like the tests aren’t reflecting that. I started testing a good handful of days ago, each day. :/ the first few test I didn’t test in the morning and they seem to be darker. Maybe I’ll take more tests later on and see what happens. I got the cheap huge box of strips off of Amazon