"He who marches out of step hears another drum." ~ Ken Kesey
when I caught that he had mixed up one of the orders after he was appalled that I went behind him even after he ASSURED me it was correct he went to blaming it on the customer, not just a hey I messed up.
Hmmm. Well, you've had one talk with him and explained. So I'd think you want to take documentation steps in the next meeting. This kind of sets the tone for seriousness. He should slow down with his behavior if he wants to stay there. If you need another talk, then, he prob isn't able to change.