Can't change laptop screen backlight brightness after upgrading to 13.04

view full story

http://www.kubuntuforums.net – I have an Asus laptop that I installed 12.10 on some time ago. At first, I was unable to change the screen brightness via the keyboard or power management settings, but I was able to fix this by adding "acpi_backlight=vendor" to GRUB_CMDLINE_LINUX_DEFAULT in my GRUB settings. After upgrading to 13.04, this fix no longer works and I'm back to being unable to change the screen brightness. I've tried a fresh install of 13.04 as well, but that didn't solve the problem. I suppose I should mention that with the "acpi_backlight=vendor" GRUB setting, I have two entries in /sys/c (HowTos)