Flex :: Images Will Not Dynamically Refresh

I am writing a Flex application to receive xml from an httpservice. That works because I can populate a datagrid with the information. The xml sends image pathnames. A combobox sends a new HttpService call onChange. This repopulates the datagrid and puts new images in the folder that flex is accessing. I want to dynamically change the image without changing the pathname of the image.
<mx:Canvas id="borderCanvas"><mx:Canvas id="dropCanvas">
<mx:Tile id="adTile"><mx:Image></mx:Image>
</mx:Tile></mx:Canvas></mx:Canvas>

This is my component. I assign my Image sources using this code:
var i:Number = 0;
while ( i <= dg_conads.rowCount){
var img:Image = new Image();
img.source = null;
img.source = imageSource+i+".jpg";
adTile.addChild(img);
i++; }

My biggest problem is that the images are not refreshing. I get the same image even though I've prevented caching from the HTML wrapper and the ASP.Net website. The image automatically loads in the folder and refreshes in the folder but I can't get the image to refresh in the application. I've tried
removeAllChildren();
delete(adTile.getChildAt(0));
And neither worked.