SwapDepth multi-instance prob

Hey i have a RPG game in the making, and i have a character who can walk in 8 directions.

I can do hitTests etc…

but when i found this TUT on swapDepths i was amazed!

so i gave it a go. worked fine on same instance (or _root)

but cant get it to work through diff. instaces;
eg.
instance called “world” has the character in and an object1.
instance called “stuff” has an object2.

all have
"
onClipEvent (enterFrame) {
this.swapDepths(this._y);
}
"
but the depth only works on “object1” not “object2”

PLEASE HELP!