Ovulation, when..?

Nadja
Took two ovulation tests yesterday (afternoon) and one before bed. The first was "almost" positive.(almost as strong color as the C) and some hours later i took another and it was clearly positive! (About 6pm). Then again i took one before bed and it was 100% negative.. So have i ovulated around 6pm then? Did i miss it if i had sex that evening around 24:00? Hmmm:/