O's on clearblue advanced digital?

 I decided to use an opk this month while ttc. I like the clearblue advanced digital because it seems easy enough to read with the smiley or no smiley. Today I'm cd15 and still no flashing OR solid smiley! Im starting to feel down. I was predicted by two different apps, including glow, to ovulate yesterday. I feel like I should have at least had a flashing one already! Did this happen to anyone else??