Markus,
Take a look at the property nodes, just right-click over the control that you want to manipulate and go to create and select property node. From there you can select what property you want to read or write, one of then is the value, this way you can change the value of a control o read the value of an indicator.
Also you can use the mechanical action to see if that gives you the behaviour that you expect. just right click on the control and got o mechanical action, try playing with the switcha nd latch options.
Hope this helps.
Regards,
Juan Carlos
N.I.