OPK question.. Help!

Hi all. Second month using OPK. Last month I had a high surge on day 15. I am testing twice a day, afternoon and evening time. I have a regular cycle lasting anywhere from 28-30 days. I am on day 15 today and I am still getting low lh levels/ negative readings on the clear blue easy read. Did I miss my peak or do you think it hasn't occurred yet? Help!