Display brightness buttons don't change the setting.

I have a Dell XPS 15. After finally getting round to installing the free Windows 8.1 update for my system, the brightness controls have stopped working. The OSD appears and the level slider goes up and down, but the actual level doesn't really change.

I have tried to uninstall the quickset64 application and reinstall it. That doesn't seem to have worked. I even tried to uninstall the Intel HD4000 drivers and reinstall, but after unistalled and rebooted, it looks like windows automatically installed them, then when I went to install the version downloaded from the dell website it said they were older, so I didn't bother installing,

Does anyone have solution, or even a simple step by step for me to go through to get this working. It gets really annoying especially at night when the screen is set on 100% brightness.

I found this post and tried the steps in there to no success, just using my systems equivalent drivers:

http://en.community.dell.com/support-forums/laptop/f/3518/t/19516193.aspx