Can't Adjust Screen Brightness

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http://forums.fedoraforum.org – I tried using Fn+<- to turn the brightness down, and it showed the little sun icon indicating the brightness was turning down, but it didn't do anything. I also tried xbacklight -set 100 but that didn't do anything either. How can I adjust my backlight? The default screen brightness is just too high to use. I also had this problem on Ubuntu, but I kinda solved it by using a Bash script to adjust the brightness. But that script doesn't work in Fedora. (HowTos)