Apple’s Pro Keyboard, introduced at Macworld Expo, New York, has a compatibility problem with older Macs, Apple has confessed.

In an email sent to customers who have pre-ordered the device, Apple acknowledges the problem and promises a refund.

The keyboard’s volume-up, volume-down, mute and media-eject keys don’t work on Macs that shipped before the show. Current models don’t suffer from the problem, reports claim.

The company says support for the use of the new keys on older systems will not be implemented until early 2001.