cannot adjust brightness anymore since upgrade on 14.04

[goavelo]

on a netbook ASUs VX6
with 12.04 it worked well: Fn+F5 to make the screen less bright and Fn+F6 to make it brighter.
since upgraded on 14.04 the brightness seems to be locked.
the transparent scale on the top-right of the screen still goes on and the cursor also moves sideways but the brightness doesnt variate. only after a restart the change gets effective.
thank you for your help

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1317273/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.