Just checking - both properties are pointing at the right references in the Creation Kit?
If "Altar" is the reference to which this script is attached, then you don't need a property for it. Instead, you can simply call non-global functions on it by omitting the location:
Disable()
If you need to pass the scripted object as, say, the parameter of a function, then you can use the "Self" keyword.
If these two references will always be paired up in such a way that one is enabled and the other disabled, then you could use http://www.creationkit.com/Reference#Enable_Parent so that you only need to http://www.creationkit.com/Enable_-_ObjectReference/http://www.creationkit.com/Disable_-_ObjectReference one of them.
Cipscis