Coop, sounds like you need to "step away" from this issue. Clear the brain a few days, let the clouds and smoke dissipate, let the new spring come in, and when you get back on it, go through each step again, don't assume anything, study, then execute.
What I'm trying to say is "the problem might be right in front of you but you just can't see it".
Happens to me more and more and more.
Good Luck