Potential causes of communications trouble are:

- the controller is not connected to the Macintosh,
- the cable between the controller and Macintosh is not the correct one,
- the controller cable is not connected to the same serial port as Thinking Home has selected,
- other software is trying to use the same serial port, making it unavailable to Thinking Home.
- the controller cable was temporarily disconnected. See details for more information.

Also, check out the other info on troubleshooting communications.