I had a section of code that was locking me into a valid event and never letting go. The bottom line was that it was failing the valid check on a between comparison. After looking at it and the help I can understand why, but just thought I would throw this out here since it might bite someone else. Bottom line:

betw(50, 1, 100) = TRUE
betw(50, 100, 1) = FALSE
betw(-1, 0,-100) = FALSE (this is what got me since I was using variables) => Between (adjust_amount,0,due_amount) should be valid but wasn't. The fix is easy, but it got me.