Ovulation test

Hi! 
i have being trying to conceive using the clear blue ovulation digital kit. I got 4 days of flashing smileys (did the baby dance) and had the 48 hours of solid smiley (did the baby dance). Then the day after the 48 hours I had an empty circle. Then the next day I tested again just for fun and to keep track of everything and it was a solid smiley again????? Anyone know why or what this means? Thanks :)