I know this is a known bug, it been asked and answered thousands of times before. I've spent the past couple of months searching for a solution and all have failed.
My Fn keys won't adjust brightness and if I go to system setting > Brightness and Lock the brightness bar seems to appear for a split second then disappears.
echo 5 > /sys/class/backlight/acpi_video0/brightness
changes the value of the brightness but the brightness does not actually change.
I'm using ubuntu 12.04 lts on a toshiba satellite C50D