change display brightness

[marchello_lippi2]

Hi all,

How do I change display brightness?
I do have [less-brightness] and [more-brightness] keys on my notebook keyboard, but they do not change situation.
Yes, I can see that brightness [status] changes upon pressing buttons, but actually my display brightness doesn't change.

My main desktop environment is Lubuntu notebook 14.04.1 LTS

Upd: my notebook is Dell Inspiron 15 3000 Series.

[marchello_lippi2]

Anything?

[xc3RnbFO8P]

It is a bug.
My brightness work in Kubuntu session but not in Unity
http://ubuntuforums.org/showthread.php?t=2250862