6 days of flashing smiley and NO peak smiley?????

Hi! I'm so frustrated. Has this happened to anyone?? I had 6 days of the flashing smiley on OPKs I use clearblue advanced digital. This morning is the 7th morning I tested (CD15) and it was Low, a round circle!!! I did not see a peak smiley. Should I test again? I did have to open a new pack of testers for this morning. Could that be it? Has anyone else not had a "peak" day after so many flashing smileys?? Thank you!