What's wrong with code?

[ash_at_risk]

I m annoyed with the code , it has been compiled without errors , but the screen is shown blank…

var numTrees:Number = 100;
var fl:Number = 250;
var gravity:Number = .5;
var vx:Number = 0;
var vy:Number = 0;
var vz:Number = 0;
var friction:Number = .98;
var trees:Array;
var vpX:Number = stage.stageWidth / 2;
var vpY:Number = stage.stageHeight / 2;
function Trees()
{
init();
}

	  function init():void
	{
		stage.align = StageAlign.TOP_LEFT;
		stage.scaleMode = StageScaleMode.NO_SCALE;
		
		trees = new Array();
		for(var i:uint = 0; i < numTrees; i++)
		{
			var tree:Tree = new Tree();//Tree is the movieClip in library
			trees.push(tree);
			tree.xpos = Math.random() * 2000 - 1000;
			tree.ypos = 200;
			tree.zpos = Math.random() * 10000;
			addChild(tree);
		}
		addEventListener(Event.ENTER_FRAME, onEnterFrame);
		stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeydown);
	}
	
	  function onEnterFrame(event:Event):void
	{
		for(var i:uint = 0; i < numTrees; i++)
		{
			var tree:Tree = trees*;
			move(tree);
		}
		vz *= friction;
		sortZ();
	}
	
	  function onKeydown(event:KeyboardEvent):void
	{
		if(event.keyCode == Keyboard.UP)
		{
			vz -= 1;
		}
		else if(event.keyCode == Keyboard.DOWN)
		{
			vz += 1;
		}
	}
	
	  function move(tree:Tree):void
	{
		tree.zpos += vz;
		
		if(tree.zpos < -fl)
		{
			tree.zpos += 10000;
		}
		if(tree.zpos > 10000 - fl)
		{
			tree.zpos -= 10000;
		}
		
		var scale:Number = fl / (fl + tree.zpos);
		tree.scaleX = tree.scaleY = scale;
		tree.x = vpX + tree.xpos * scale;
		tree.y = vpY + tree.ypos * scale;
		tree.alpha = scale;
	}
	
	  function sortZ():void
	{
		trees.sortOn("zpos", Array.DESCENDING | Array.NUMERIC);
		for(var i:uint = 0; i < numTrees; i++)
		{
			var tree:Tree = trees*;
			setChildIndex(tree, i);
		}
	}