Positive digital opk but negative cheap strips

When TTC with my daughter we just used clearblue digital opk and were pregnant 1st month.

Now TTC number 2 we use both and noticed that when clear blue says its peak my cheap strips are negative..I keep testing for days after using strips but never had a very dark positive opk? Am I even ovulating?

It's month 4 now and still not pregnant..I did have Mirena coil removed 5months ago but always had regular periods on it and still do!