Opk testing and confused!

Hi ladies!!! I'm new to all of this and using the opk trips to try and find out when I'm o'ing. Have been using them the last few days around noon and no luck. Took one this morning and got a positive (when I first woke up as suggested on the instructions) tested again at noon and had a negative?!?!? Do you think I had the surge and just happened to catch it this morning? Help!