Using Tween class in AS2.0

I’m using FlashCS3 with AS2.0. I am trying to create a movieclip button which controls the properties of another movieclip.

In my actions layer I have:
import mx.transitions.Tween;
import mx.transitions.easing.*;

On my movieclip:
on(release){
_root.attachMovie(“myform”,“myform1”,200);
_root.myform1._x=200;
_root.myform1._y=200;
var fading:Tween = new Tween(myform1, “_alpha”, Elastic.easeOut, 0, 100, 10, true);
}

It gives me the error message of not being able to load the tween class.
Can someone help me with this?

Thank you.