Laptop brightness not functional

[fruitmachine]

Hi, I recently installed linux for the first time and it's been great so far except for one issue. I cannot adjust my laptop's screen brightness. I've searched other threads and tried their solutions, but none have fixed my problem.

Here's the description:
I cannot change the brightness using the System Settings > Screen > Brightness slider, nor the laptop keys to change the brightness (but the on-screen slider appears showing that it's trying to change the brightness).

What I've tried:
1. Changing the line in /etc/default/grub

Code: Select all

GRUB_CMDLINE_LINUX=""

to

Code: Select all

GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

That did change my problem a bit. Now instead of being at 100% brightness all the time, it now dims to about 50% brightness when I unplug the laptop from a power source. But still no control otherwise.

2. Installing and trying to use xbacklight, to no avail.

3. Using cinnamon's brightness applet, which when I try to use, crashes the UI and disables the keyboard (but not trackpad strangely enough).

My system:
Samsung NP-Q430 running Linux Mint 12
inxi returns:
Graphics: Card: nVidia GT218 [GeForce 310M] bus-ID: 02:00.0
X.Org 1.10.4 drivers nouveau unloaded: vesa,fbdev Resolution 1366x768@60.0hz
GLX Renderer Gallium 0.4 on NVA8 GLX Version 2.1 Mesa 7.11 Direct Rendering Yes

Any input is appreciated, mint has been a great experience so far except for this minor hiccough which I'd like to fix (using the computer at night with 100% brightness pains my eyes, and trying to use my laptop in the sunlight at 50% brightness is near impossible). Thank you!

[wasicu]

Have you tried the Fn+key to the right of the right-hand Shift key or Fn+key below the one to the right of the right-hand Shift key combination?

[fruitmachine]

Both the Fn keys have the same results.