macbook pro keyboard backlight

I can't adjust my keyboard backlight on my 15in unibody macbook pro. I downloaded labtick and I can adjust it, but i can't use the function keys. It always just comes up with that cross through the circle icon. I've tried it in dark places, light places, and with auto screen brightness adjust on and off. Any thoughts. This has worked in the past, i just havent noticed it hasnt worked until now.

-quinn

I had the same problem today for the first time. I got my (mid 2009) 15in unibody macbook pro in November. Its never happened before, and it seems to be intermittent. The cross through the circle icon seems to make me think its by design or something. Does anyone know what might be causing it? I can find nothing on the apple websight or the manual.