I'm new at as3, maybe thats the reason why i don't understand, why the setInterval causes an error.

<mx:Script>
    <![CDATA[
        import flash.utils.setInterval;
        import mx.controls.Alert;

        [Bindable]
        public var MyInt:int = 500;

        setInterval(function():void{ ++MyInt; },1000);

    ]]>
</mx:Script>

I have a label where the value of MyInt gets visible, the bind works perfect, i've tested it several ways, and i i create a button it grows the number, but if i use the setInterval function i get an error: Access of undefined property myInt.

Why? What does cause this? Please explain it, so I can avoid errors like this. Thanks