Why can I not lock the feature "automatic change of grafikmodi" as described at the supports site?

My mbp 6,2 with mavericks has some problem with the grafikcard.

so I wanted to lock the unchecked feature "automatischer wechsel der grafikmodi" in Systemsteuerung. every time the machine reboots the system goes back to the more energy efficienct option....is there some way to lock this so that the system will do as I want? any help apreciated.

by the way...on the supportsite : http://support.apple.com/kb/HT4110?viewlocale=de_DE

you can see, that there is a lock option below...this locker symbol...but on my Systemsteuerung under the point energysaving it is not....