Clearblue advanced

So I used clearblue advanced the two last times that I got pregnant and they worked great I conceived the first month trying with both my babies! I'm trying to conceive again and that is my first month,this time I'm not so sure about those tests. I have 30 CD and normally ovulate around 16cd-17cd, but this time the tests said that I ovulated around 13cd-14cd! I just don't understand... so I was wondering how was your experience with clearblue advanced did they worked for you ?