PMDG 737NG & USB Flight Sim Yoke from CH Products

I've just purchased the USB Flight Sim Yoke from CH Products, and I'm now using it together with the PMDG 737NG. Wow! What a difference:DSuddenly, manual flight has become as easy as driving my car!Just one thing that got me a little frustrated. I assigned the "Autopilot Master Switch" (A/P disconnect) to a button on my Yoke (the forward left button to be exact). This command is by default mapped to the 'Z' key in MSFS. When I attempted to disconnect the A/P in the PMDG737, the A/P disconnect sound for the default King Air sounded, and the A/P wouldn't disconnect! I then hit the 'Z' key, and the autopilot disconnected (?). I assume that the Yoke button just emulates the 'Z' key, thus the autopilot should disconnect!Any suggestions ??Best regards,