Array + random

programming flash
1 

var Count:Array = new Array();

trace (Count)
// _level0.thumbnails.thumb0,_level0.thumbnails.thumb1,_level0.thumbnails.thumb2,_level0.thumbnails.thumb3,_level0.thumbnails.thumb4,_level0.thumbnails.thumb5,_level0.thumbnails.thumb6,_level0.thumbnails.thumb7,_level0.thumbnails.thumb8,_level0.thumbnails.thumb9,_level0.thumbnails.thumb10,_level0.thumbnails.thumb11


bttn.onPress = function() {
    var myRandom:Number = random(Count.length);
    var goAnimate = animationClips[myRandom];
    var fadeTween = new Tween(goAnimate, "_alpha", Regular.easeOut, goAnimate._alpha, 0, 20);
};

Since
Count.length = 12
its like
myRandom:Number = random (12);

How to make sure, i am cycling between random (12)
Without getting the same results.
But just a cycling between 1 and 12, properly.

Greetz