I learned the hard way, and I'm sure frustrated Canary in doing so, that Armory does not digitally sign in a way that is compatible with the bitcoin-qt method, so make sure you don't sign it with Armory. (My understanding is that compatibility will come to Armory later)
I also learned this the hard way and was in a rush to get bitcoin-qt setup and signed a new message. Hopefully neither of our cubes are delayed because of it . .