Continuous/looping animation with AS 2.0?

this is probably asked a zillion times but how do I script a movieclip to repeatedly fade/move/scale from x to z back to x to z again and again…

I’ve tried onEnterFrame with …if statements and whatnot but with no luck.

my_mc.onEnterFrame = function() {

if (this._alpha <= 0){
this._alpha += 5;
if (this._alpha >= 100){
this._alpha -=5;