The mouse or pointing-device cable is securely connected to the server.
If you are using a pointing device, the keyboard and mouse or pointing-device cables are not reversed.
The mouse or pointing-device device drivers are installed correctly.
The server and the monitor are turned on.
The mouse option is enabled in the Setup utility.
If you are using a USB mouse or pointing device and it is connected to a USB hub, disconnect the mouse or pointing device from the hub and connect it directly to the server.
Replace the following components one at a time, in the order shown, restarting the server each time: