I execute this in my Mint 7 and use it to control the brightness of the screen.

xrandr --output LVDS --set BACKLIGHT_CONTROL native
I upgraded to Mint 8 and after executing the same, I got this output

jun@jun-laptop ~ $ xrandr --output LVDS --set BACKLIGHT_CONTROL native
X Error of failed request:  BadRROutput (invalid Output parameter)
  Major opcode of failed request:  149 (RANDR)
  Minor opcode of failed request:  15 (RRGetOutputProperty)
  Serial number of failed request:  26
  Current serial number in output stream:  26
jun@jun-laptop ~ $
I'm not sure about the output since I am using the same laptop and was kinda expecting to have the same results. After all, I just upgraded the version of the same Distro. I would really appreciate if somebody can help me understand this. And also, perhaps help me in making the brightness control work again.