My new MBA is the first computer I've had with a backlit keyboard, and I love it. But I don't quite understand the settings. I have the keyboard system preference set to automatically illuminate the keyboard in low light. With this on, the keyboard brightness buttons (F5 and F6) sometimes don't do a thing (the keyboard will stay dark and the on-screen indicate shows a circle with a line through it, clearly saying the function is not available). Other times they'll let me pump the brightness up and down. Then, occasionally, I'll be working in a dark room and the keyboard won't light automatically, despite being set to automatic, and I need to manually control the light - when I press F6 to brighten it, the indicator tells me it was set to zero illumination. Is the automatic control flaky? By pressing the manual buttons, have I overridden and messed up the automatic setting? I was under the impression that if I had it on automatic, it would control the brightness by itself. Indeed it seemed to do that when I first got the computer this week - the keyboard would brighten and dim according to the ambient light.