Is your iBook G4 a 12" 1.33Ghz model or a 14" 1.42Ghz model ? These ibooks motherboards (most of the time the 1.33) have a problem with the airport socket. It's a well documented issue on the web. The airport/bluethoot socket has a flaw causing kernal panicks events and often not recongnising the card. Many people tried to repair the ibook inserting a small folded piece of paper under the grey plastic bracket screwed on the airport card to put more pressure on the card connection but the repair don't last very long so replacing the motherboard seems to be the only way to do the repair. You may also take off the AP card and use a wireless USB dongle available for cheap online.