Did not get a peak positive ovulation day 15

I did not get a peak on my fertility monitor or my Wondfo test strips. They both are negative first time that happened usually I ovulate on days 10 12 13 and 14. Today is day 15 of my cycle negative. I really don't know what to think about it. Did the surge just not pick up maybe it's not high enough . Did this happen to anybody can you let me know.