Q: pairing apple wireless keyboard A1314

I'm trying to set up an Apple Wireless Keyboard A1314 on my Power Mac G5. It is discoverable and says it's connected but it won't pair. When I type in the passkey in order to pair it comes back and says it was unable to pair the device be sure it's turned on and discoverable which it is. When I turn on the keyboard the little green light flashes two quick times continually but when I type in the passkey it goes out.