not understanding

Tee
Today is the day that I suppose to ovulate. I been using the OPK strips for 5 months now. I am not understanding why my OPK test is showing negative. The OPK strips are always accurate. Could this be a late ovulation month? This never happen before. AF is due Dec 26th I am Hoping and Praying for a BFP for Christmas 🙏🏽👶🏽