CMD A will not work

[sd75lover 0]

on my most recent flight i took off and tried to engage the autopilot system, however when i pressed CMD A the light would just light up for a couple seconds, and then the A/P DC alarm would ring, but i was able to use CMD C and CMD A, is there a cause that CMD A would Work?

 

This also frequently happens on my NGX, where only one autopilot would work...

[scandinavian13 5,192]

This usually means that your hardware is interfering with the sim. Check your calibration. If necessary, there's also a setting in the PMDG SETUP > menus to tell the plane to ignore your hardware entirely when the AP is on.

[sd75lover 0]

This usually means that your hardware is interfering with the sim. Check your calibration. If necessary, there's also a setting in the PMDG SETUP > menus to tell the plane to ignore your hardware entirely when the AP is on.

I am able to enagge CMD B AND C why not A specifically?

[adamant365 28]

I would say it's possible that the ability to engage one autopilot but not the other is coincidental. Do as Kyle suggests and enable the setting to ignore control inputs under A/P.