I dont understand why the damn circle wont tween?

Quote
function init() {
var stage = new createjs.Stage("game");
var tweens;
tweens = [];
var circle = new createjs.Shape();
circle.graphics.beginFill("red").drawCircle(0, 0, 50);
circle.x = Math.random()*500;
circle.y = Math.random()*300;
var tween = createjs.Tween.get(circle).to({x:1, y:1});
tweens.push({ref:circle});
stage.addChild(circle);
circle.addEventListener("click", function(event) { alert("clicked"); })
stage.update();
}