There are a number of possible causes if your trackpad button doesn't respond which could affect either a PowerBook or iBook computer.
- It is possible that the issue may be caused by a peripheral that has been attached to the computer. Disconnect any USB or ADB devices such as mice, keyboards, or joysticks and see if the issue still persists. If this resolves the issue then it could be an old version of the software that supports this accessory device, or it could be a hardware issue or incompatibility. You should refer to the vendor of the accessory for driver updates or service for the product.
- It could be a hardware issue with the trackpad button itself. If you need to use the computer until you can have it serviced, you may, depending on the iBook or PowerBook model you own, enable the Clicking feature in the Keyboard & Mouse pane of System Preferences (in Mac OS X) or the Trackpad control panel (in Mac OS 9).
When you enable the clicking feature, you are able to tap on the trackpad to duplicate the same action as clicking on the trackpad button.
Keyboard & Mouse pane of System Preferences in Mac OS X
Trackpad control panel in Mac OS 9
Note: Not all PowerBook models support the clicking feature in the Trackpad control panel. On those that do not, the "Use Trackpad for" section will not be displayed in the Trackpad control panel.