flashing smiley to no smiley

I've been taking the digital opks 2 times a day. For 7 days I have gotten the flashing smiley and i've been waiting and waiting for it to become solid. This morning (days 7) at 11am, it was still flashing. Now, at 11 pm.. its negative. I have held my urine for exactly 4 hours. We didnt bd lastnight because we were planning to tonight in hopes that i would ovulate tomorrow or something but now im really confused and bummed as to why this happened..