Object reference variable keeps changing back into None.

I have an actor blueprint X which is derived from parent class Y which is derived from Actor. When its event graph receives an event, an instance of X sends an event to an object reference of class Y (roughly: you open a door and an openable object behind it starts moving, where a door is a subclass of an openable object). This object reference of class Y is stored in an editable variable.

The problem: when I place an instance of X into a level and set the variable to an object reference of class Y, then as soon as I click Play, it unsets itself back to None. No matter how many times I set it back (madness is doing the same thing and expecting a different result, right?) it just doesn’t stick.

I have a different blueprint Z which does largely the same thing and it works perfectly.

I can’t begin to think of what’s wrong. Anyone?.. :frowning:

http://i460.photobucket.com/albums/qq330/kaiyinai/Puppies/baileys-puppy-eyes-21130931.jpg