A keycam is a sub component inside a cylindrical chassis (such as AL or ND) that provides the interaction required to lock and unlock the chassis.
 Cam Lift Hinges are specially designed hinges used mainly on acoustical door assemblies. The Cam Lift Hinge lifts the door during its travel and seats the door bottom for a pos...
The keycam may have failed, example here, the latest design keycam can be easily identified as the colored changed to black. Replace either the keycam or chassis as needed...
 This could also happen if the tailpiece isn't installed in a KIL, FSIC, or SFIC cylinder.  The FSIC driver also could have come loose from the core in the spindle.
The Exit Alarm takes a 1 1/8" Mortise cylinder with a straight cam. See first page of Exit Alarm inst below. Exit Alarm inst
Von Duprin KR (key removable) mullions requires a 1-1/8" or 1-1/4" mortise cylinder with the standard straight cam, the cam is not inverted. Please see chart below for part numbers. 
The KR4023 mullion requires a 1-1/4" mortise cylinder with straight cam. This is stated in box 7 on the first page of the KR4023 mullion instructions.