"Cannot Use that Class" message????

[Bixby]

I know if a piece is dyed a different color it will just give a warning, but still equip, but I'm pretty sure any piece being missing will cause it not to equip anything from the set.

It's only the main weapon/tool. Just this morning, I went through 3 of my level 15 DoH sets. The shirt was missing for every one. Every one successfully equipped, just with unexpected sexiness and a warning. I also had this happen with pants, wrists, and gloves just this weekend. If the neck slot is a problem, it's an exception, not the rule.