Positive OPK in the AM

Carmen
I have been using the clear blue digital and it finally had a solid smiley (8am). This afternoon (around 4pm) I tested negative. Why and what does that mean? Did I miss my ovulation?? Also, finished (1st round) Clomid last week, and had ultrasound on Monday, there were TWO follies but my right was more dominant than the left one.