I recently installed Ubuntu 12.04 alongside Windows 7 in a Vaio T13 ultrabook.
I cannot use the the Fn+F4 or Fn+F5 to change the brightness. The bubble appears indicating that brightness is being changed but with no visual impact on the screen.
I've tried many solutions involving the manipulation of the /etc/default/grub file but none of them worked. Whenever I tried this manipulation the screen still didn't change, however the bubble stopped functioning properly.
This is not a problem of the Fn shortcut. Even when I try to change it in the Brightness and Lock on System Settings, the bar does scroll but the screen remains unchanged.
Does any one has a way around this mystery?