Griffin Technology

When I connect the iMate I get the message "Device unknown ... not enough power".

Make sure the iMate is connected directly to the computer, not the keyboard. The iMate needs to be able to support multiple devices that may or may not require more power than is available from the keyboard. The keyboard is what is termed an "unpowered hub". The ports on the iMac are powered hubs and can provide far more power for devices. If you do not have a port available on the iMac you can purchase a powered hub such as the Griffin USB Audio Hub. This will allow you to connect several devices that require more power.