The Get/Set Var calls only work with variables defined within Char/ItemScripts. If no such variable exists within the scripts the Character/Item uses, then nothing occurs.
I don't think that's quite true actually, I'm using a couple variables calls in my story and none of them point to anything used in char/item scripts though they work perfectly. I've also tried using them and them not work so well.. Not sure what the issue is there.
