how to change image src of div from ajax

 $(document).ready(function () {

$(".Zoom1").click(function () {
alert("zoom");
ImgName = this.name
$.post("/Controls/ZoomTo.ashx?ImageName=" + ImgName + "&Add=1", {},
function (response) {
if (response != ' ') {
$('#ScrapZoomImg').src="response "
}
});

Html :

    <div id="ScrapZoomImg"></div>

AShx :

Public Class ZoomTo
Implements IHttpHandler
Implements IRequiresSessionState
Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest

Dim imgname As String = context.Request.QueryString("ImageName")
Dim PageId As String = HttpContext.Current.Session("ClientId")
Dim dsBk As DataSet = ScrapBookHelper.GetScrapbookZoomImages(imgname)

HttpContext.Current.Session("ZoomImages") = dsBk.Tables(0).Rows(0).Item(2)

context.Response.Write(HttpContext.Current.Session("ZoomImages"))
End Sub
ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
Get
Return False
End Get
End Property

End Class