So I used a Clearblue OPK this month and I never got a smiley face

After using a Clearblue Digital OPK this month and never getting a smiley face I'm now concerned that I don't ovulate.

I'm a regular 30 day cycle and AF arrives like clockwork usually (only 1 time it was late).

Anyone experienced this before? We've been TTC for about 7 months now.