fn + arrow keys don't adjust actual brightness on an Acer Aspire 5740

I have an Aspire 5740 with an Intel Core i3, and Fn + arrow keys still call up the brightness adjuster, but have no effect on actually changing the brightness. The slider moves, but the brightness remains at maximum. System settings also allow me to move the slider, but again, with no effect.

It's killing my battery - please tell me what to code in to fix this!

Solution 1:

It's a known bug. You can view it here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/543294 Well someone posted a workaroudn like this:

1. Open a terminal (Program - Accessories - Terminal)
2. Type in "sudo gedit /etc/default/grub" (without the "")
3. Find the line that says: GRUB_CMDLINE_LINUX="quiet splash"
4. Edit it so it says: GRUB_CMDLINE_LINUX="quiet splash acpi_backlight=vendor"
5. Save and exit
6. Run the command "sudo update-grub" (again without quotes of course)
7. Reboot and enjoy!

and yeah, it worked for me