Confused about OPK

I have been testing with Clear Blue Digital this cycle with FMU and have not shown any LH surge. Yesterday, I forgot about testing in the am and when I tested last night I got my first smiley face indicating Lh surge and the stick was definitely as dark as the control. Tested again this morning with FMU and it showed no LH surge. Is this normal? Am I getting ready to ovulate or not? Thanks for all advice!