wifi password connection failed

I have and older 15" G4 power book with OS X 10.5 installed everything works great, except the wifi.

When I try to connect to my wireless network, it continually states the password is incorrect, and connection failed.

I heve tried the same password on all my other devices, ipad, Mac book pro, 13",15" they all work fine with the same password.

Why wont the G4 accept the wifi password?