PS2 port has power but will not accept input from keyboard

I have a Compaq sr5413wm that is not accepting input from the keyboard PS/2 port.
Both PS/2 port have power.
I have been using a KVM to connect it to a sender system without problem. The second system in working without problem, so I know it’s not in the KVM.
The KVM get it power from the PS/2 port. On power on it will come on and connect the monitor and mouse. This is how there is power on the PS/2 port.
I have tried using 3 different keyboards with any luck.