Help class problem

1 
class ControlPanel extends MovieClip {
    var Nav:Array = new Array("nav1", "nav2", "nav3", "nav4", "nav5", "nav6");
    var Url:Array = new Array("http://www.test1.com", "http://www.test2.com");
    function ControlPanel() {
        Stage.showMenu = false;
        Stage.scaleMode = "noScale";
        for (var i:Number = 0; i<Nav.length; i++) {
            var currentURL = Url*;
            var currentNav = Nav*;
            _root.nav[currentNav].onRollOver = function() {
                this.gotoAndPlay("OVER");
            };
            _root.nav[currentNav].onRollOut = function() {
                this.gotoAndPlay("OUT");
            };
            _root.nav[currentNav].onPress = function() {
                trace(currentURL);
            };
        }
    }
}

when i press button it giving me undefined why is that?