Learning to Tween - what am I doing wrong?

programming flash
1

Hi. I get this message: Scene 1, Layer ‘Layer 1’, Frame 1, Line 5 1119: Access of possibly undefined property EaseIn through a reference with static type Class.
Here’s my code:

import fl.transitions.Tween;
import fl.transitions.easing.*;
import fl.transitions.TweenEvent;


var myTween:Tween = new Tween(shape, "x", Elastic.EaseIn, 0, stage.stageWidth, 1000, true);