Help:convert to as2

I am trying to convert AScrip 1 which is onClipEvent
to AScript2.0 and put it to main timeline. I thought I can do it, but after one hour I gave up. What do I do wrong?

//flash mx 6 and as1.0
//onClipEvent (load){
// tX=200;
//convert to as2
var tX:Number = 200;
boxMove.onEnterFrame = function():Void{
aX=(tX - this._x)*.2;