[flexcoders] Why cant I use mouseOver() in Image class, but using

[yossi.baram]

Hi,
I have a dataGrid, and in one of the columns I call an ItemRenderer 
(ActionScript).
This renderer should create a list of images as follows:
override public function set data(value:Object):void {  
        if (value != null)
           {            
                removeAllChildren();
                for (var i:int = 0; i < value.hair.length; i++){
                var img:Image = new Image();      
                img.source = value.hair[i].image;      
                img.id = "image - " +i;
                img.height = 20;      
                img.toolTip=value.hair[i].width;
                img.percentWidth=value.hair[i].width;     
                img.maintainAspectRatio=false;
                addChild(img); 
            }     
        }
}

All images are displayed side by side in a cell, as I wanted.

The problem is that I need to use img.toolTipCreate to catch an event 
on each of the images and It doesnt let me, why?
If I use <mx:Image tag in mxml file, it lets me use this function but 
in my ActionScript it doesnt.

What is the different between this 2?
Thanks for any advice

Jo