Weird!!!

So as you probably know i got a few positive tests and a few negative. Thought i had a chemical, but i took a pregnancy test tonight and it was positive. But this is the weird part: it was only positive after i opened it. I know you're going to say i shouldn't have done that and it was invalid after i opened it, but the weirdest part is after i closed it again, put the top part back on, and looked for the line it had disappeared. I'm so confused! Does anyone know what this could possibly mean?! Thanks for any answers