HI, 
Peter is on holiday, but someone maybe could help. 
I mapped my MCP and a RP48 to use the PMDG 737. 
Everything works but something is strange. I mapped the "on/off" autopilot button and, when I switch it off in flight, I cannot switch it on again using that particular button. 
BUT, I also mapped in on my yoke and, with this button, it works fine, I can switch it on and off without any problems. 
Could someone try to repro this and tell me if it works for them ? 
--> Take off 
--> Turn on autopilot using MCP on/off button 
--> Turn off autopilot using MPP on/off button 
See if it works. Sometimes, I can do it twice but it will not work the third time. It make a sound like if the autopilot was disengaged. 
Very strange. Not a catastrophy since I can use the button on the yoke (great for emergency switch off), but I would like to know if it comes from my system. 
THanks 
Olivier