Wondering..

Hello ladies, I've been using opks, for the first time this month. (After taking clomid) for four days, I had the flashing smiley, I tested two times a day.. So yesterday morning the flashing smiley came out, since I ran out of test sticks I bought some last night and got the blank circle.. I tested again this morning and again I got the blank circle.. Has anyone one experienced this? Does this mean I did not ovulate?