I'm working on an Acer Aspire E15 with Ubuntu Studio 14.04 installed in dual-boot with Windows 8.1, and from Ubuntu I'm not able to modify the screen brightness, for two reasons.
The first is that I don't find the option in the settings menu.
The second is that if I use the keyboard commands (Fn+left/right arrow) I receive this on-screen notification:
Despite the blue bar you see in the notification moves itself according to what I press, the brightness doesn't change.
On Windows I don't have such problem, so I know it's not an hardware issue.
How can I proceed to make it work?
UPDATE:
I tried this solution, but nothing has changed.
UPDATE 2:
Also this solution didn't work.
UPDATE 3:
The problem solved itself after an automatic system update shortly after I posted this message. But now I noticed it reappeared. So I'm undeleting this post.