My laptop is a Acer 5750G. I cannot change the screen brightness of my screen via the GUI but i can change it via the Terminal according to the directions on this answer: http://askubuntu.com/a/57610/126148
when i run the first command ls /sys/class/backlight/*/brightness i got two output. If i change the brightness on acpi_video0 nothing happens: same on the GUI. If i change the other one: Intel_backlight, it works. My fear is that the GUI is tied to acpi_video0 that is the bad interface ( the one that doesn't work) and i need to change this. But i don't know how to do it.
Thank you very much.