If you inspect the broken image with a developer toolbar (or in the page HTML source), you may find out what the problem is - e.g. a missing image file in the new applictaion or an incorrect link to the image (e.g. an absolute URL or a wrong relative one).
Also please let me know if you are using Ajax to show the control on the page. If yes please set the EnableAjaxSkinRendering
property of this control to true in the PageLoad event on the server side.
the Telerik team