Help!

So this morning with FMU I got this positive ovulation result:

But I just read that I shouldn't be doing these with FMU...so I just took another one and this is the result:

So.. am I actually not going to be ovulating then? I'm so confused!! I'm just going to keep taking these dang things and having sex lol but I just want to know why it would go from such a clear positive to a negative in just a matter of a few hours.