Autopilot problem

I did a few tests last night, and discover the following problems:
I am using the default 747 autopilot on the JBizz, and found that
I am using the default 747 autopilot on the JBizz, and found that
- when the A/P is switched on, I can select the NAV Hold and the HDG Hold simultaneously, which is not correct.
- When I select altitude hold, it does not work, but the moment i switch it off, the nose pick up or drop, which tells me it does have an effect, but not working correctly
- When I switch on the HDG Hold or NAV Hold, the Flight director switch also switch to ON