Windows 8 Brightness Issue

I recently installed Windows 8 Pro on my Sony Vaio notebook.  I have just about everything I can think of configured to my liking, except for 1 thing that is really bothering me.  My brightness function keys on my keyboard no longer work (Fn+F5 and Fn+F6).  I can adjust the brightness from the settings section in the charms bar but not with my function keys. I have tried installing all possible drivers and have had no luck. Does anyone have any ideas or know of any programs I could possibly use to set the brightness keys?

Thanks in advance