Why doesnt it work?

[Angerpull]

Kyle is mistaken, the bust is an Entity. You've got the two of them mixed up.
AddEntityCollideCallback("Player", "Bustie", "Bustied", true, 1);
should be
AddEntityCollideCallback("Player", "triggername", "Bustied", true, 1);

You have your Collide area set to one of Busts currently, you want an EntityInteract callback if you want to do that sort of thing - but I assume you want to move the busts when it's out of the players view, so make a trigger(script area) in a nearby area that'll set it off when the player collides with that and then set triggername to what that trigger is called in the Editor.

More complex methods: after a trigger has been stepped in, and the bust looked at - activate a callback/script area that when a player looks at an area away from the bust, the bust disappears. This will make it appear more natural and allows you to do it in line of sight, whilst preventing it from being triggered by the player looking at the area outside of the trigger - from a different angle that might allow sight of the bust.

If one of the Busts is still in the doorway - check you didn't get them mixed up in the Editor - ticked the wrong one active.

Okay so could you give me a script so it works? This is just fcking confusing. I can make a cave in happen just fine, but when I try to make Busts appear in a different location, that's when shit hits the fan and the game says 'Nope'.

So a script that works would be cool.