Blimp Autopilot

There are a lot of blimps here,and elsewhere. None of them have an autopilot that works in the Heading or NAV modes. Some have autopilots that work OK in the ALT mode. What does it take to get them to work in the NAV and Heading modes? The air and aircraft.cfg files all have sections that say the autopilot is enabled and powered. Is there anything in the flight dynamics section, or elsewhere,that is required to have the autopilot to fully function in all modes, except autothrottle, which is not required? Thanks, regards, Bob.