for some reason the autopilot will not engage. press the engage button but only get the disengage warning

any ideas

You need to put that into some context, like e.g. were you flying or on the ground? Which phase of flight? What were your yoke inputs while you were doing it? What was the pitch/roll angle? etc

i have tried in all phases of flight; shortly after takeoff, climb, cruise. with neutral control input.

 

 

I had a problem recently with the Aerosoft crj where auto pilot would not engage for any reason, something changed in my control settings.   

I can't remember what exactly I did but i believe I had a conflicting assignment with the avionics master toggle and it was preventing the auto pilot from working. 

Also make sure the Yaw Damper is on.

 

 

I had this issue a while back with the CRJ and someone posted in the forums that if there are any "Yoke" inputs the AP will not engage. With any aircraft now I make sure my hands are off the yoke before engaging the AP. Seems to work for me. But I have found the ATR AP to be a little finicky lately as well.