Need help with mask modifier!

So I have a mask modifier, and I’m using it the way this guy did for his south park rig: The problem I’m having is that instead of making one modifier visible and all the others INvisible, it makes all of them visible and one INvisible. I’m not sure how to fix this, if you know how, please reply! P.S. wether or not the modifier is visible when you add the driver has no overall effect, I tried it both ways.