Okay, I’ve got it now. I completely missed the fact that you were trying to dial 933 directly. You can’t.
Here’s how 911 works: 911 is a feature code on the system. If you dial 911 without first selecting an outside line (or trunk group, or whatever), the system will dial the emergency number listed in the numbering plan, using the emergency routing and telephone number programmed for each endpoint.
If you access an outside line before dialing 911, it will ignore the feature code information and dial 911 using the outbound access for the station.
933 is not a valid feature code or extension, so you receive the error message. Why is it you want to dial 933 anyway?