OPK help please :(

I usually use the clear blue advanced opk because I don't normally get a clear positive with regular OPKs, but I only had 2 test sticks left for the clearblue so I was saving it to confirm my peak... anyway I got a positive on a regular opk last night (yay!) but that was my last one so this morning I used the clear blue and I've got a NEGATIVE! not even a high...from a positive opk last night to nothing so quick? what's going on?!