Currently Being ModeratedNov 27, 2012 6:22 AM (in response to michaelfromselkirk)
In System Preferences, Keyboard, there is a check box for "Adjust keyboard brightness..." which you can play with.
Also, if there is too much ambient light the keyboard will not light up. The light sensor is at the camera at the top of your screen. Try covering that up with your hand to see if the keyboard lights up.
Finally, if you adjust the keyboard light brightness with the F4-F5 keys, what happens?