Codice PHP:
import mx.transitions.*;
import mx.transitions.easing.*;
var tween1:Tween = new Tween(mc, "_y",Regular.easeInOut, 0, 300, 3, true);
tween1.onMotionFinished = function() {
var tween2:Tween = new Tween(mc, "_x", Regular.easeInOut, 0, 500, 3, true);}
tween2.onMotionFinished = function() {
var tween3:Tween = new Tween(mc2, "_y", Regular.easeInOut, 300, 50, 3, true);
};
tween3.onMotionFinished = function() {
tween3.yoyo();
};
cos'è che non va? 
edit: risolto..erano sbagliate le parentesi graffe chiuse