LH surge???

I've been using okp's for the last couple months. Last month they they had lines on indication ovulation matching up with what Glow was indicating. This month I have taken them every morning during my "fertile window" and not even a faint line???? Today is supposed to be "the day", but nothing. The brand is the most recommended bulk test on Amazon. So am I not going to ovulate because there apparently isn't any of the appropriate hormone present? And why would there be no LH surge?? So confused.