onMotionFinished() not working anymore?

programming flash
1

Ok, for my site i have a preloader that slides in, then it slides out once it’s finished. I decided to change a couple things, now the same file with some unrelated changes is giving me syntax errors when publishing it. Heres some code:

import mx.transitions.Tween;
preloader.bar._visible = false;
container._x = container._y=0;
var preloadTween:Tween = new Tween(preloader, "_x", mx.transitions.easing.Regular.easeOut, Stage.width+100, 428.9, .5, true);
preloadTween.FPS = 30;
preloadTween.onMotionFinished = function() {
 my_mc = new MovieClipLoader();
 preload = new Object();
 my_mc.addListener(preload);
 preload.onLoadStart = function(targetMC) {
  container._visible = false;
  preloader.bar._visible = true;
  preloader.border._visible = true;
 };
 preload.onLoadProgress = function(targetMC, lBytes, tBytes) {
  preloader.bar._xscale = (lBytes/tBytes)*100;
 };
 preload.onLoadComplete = function(targetMC) {
  var preloadDoneTween:Tween = new Tween(preloader, "_x", mx.transitions.easing.Regular.easeIn, 428.9, Stage.width*0.1-500, .5, true);
  preloadDoneTween.FPS = 30;
  preloadDoneTween.onMotionFinished = function() {
   container._visible = true;
   preloader.border._visible = false;
   preloader.bar._visible = false;
  };
 };
 trace(container._x);
 my_mc.loadClip("jj.swf", "container");
 container._lockroot = true;
};

Im getting this in the output window:

**Error** Scene=Scene 1, layer=actions, frame=1:Line 6: There is no property with the name 'onMotionFinished'.
     preloadTween.onMotionFinished = function() {
**Error** Scene=Scene 1, layer=actions, frame=1:Line 21: There is no property with the name 'onMotionFinished'.
       preloadDoneTween.onMotionFinished = function() {
Total ActionScript Errors: 2   Reported Errors: 2