i figured out a way to make it work temporarily (need to do it everytime when restart)
-use the outdate intel driver (188.8.131.5215)
-update intel graphic WDDM1.3 via windows update
-it revert to new intel driver, but now the brightness control will work as long as you dont restart.
if you do restart, all you need to do from now on (well, unless intel release new driver)
- go to device manager, update driver, select old driver (184.108.40.20615)
- repeat the steps, but this time select new driver (10.18.10.3379)
if anyone knows a better technique, please let me know
I am sorry to hear you are having problems but let me help you.
It is important to say that Intel® provides the hardware to computer manufactures and they will design and create their own drivers specifically for their units. From our side we can provide generic drivers for your unit however we strongly recommend using the original operating system and drivers provided by the OEM.
I solved the problem in my case. I am running Windows 8.1 on MacBook Pro late 2013. My IRIS driver version is 10.18.10.3412 (22.01.2014).
Turn on your computer. When it turns on, after few seconds put it into SLEEP. Ten seconds later turn on your computer again and you should be able to control brightness!