I agree - negative could just be not enough to show up. Even the ones that say they can detect early are not that sensitive if you look at the package insert. Something like 50%-75% 2-4 days prior and 80% one day prior. That's all assuming you ovulated 14 days prior to that. With this one I didn't get a positive HPT until 7 days late and then it was so faint that I was left wondering and made the Dr. order a stat HCG so I could find out for sure before the long holiday weekend. :-)