Why does the brightness control not work?

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http://askubuntu.com – I installed Ubuntu 12.10 on a Sony vpc cw18gf. I can not decrease or increase brightness and my Fn key does not work. My brightness and lock settings are as in this image: I tried both pages below but my problem is not solved. page 1: Brightness control doesn't seem to work on a Toshiba Satellite M115 laptop page 2: Ubuntu 12.04 - Brightness controls not working [duplicate] (HowTos)