OPK question! Help!

Jessica • Cleveland, Ohio. Married 10.5.13. CJM born 12.14.15.
I took an OPK this morning when I first woke up and I got a smiley face so it's a fertile day. However,  when I got home @ 3 i took another one and no smiley face.... Does this mean I'm not ovulating anymore?? Orrrr my urine was just too diluted maybe....?