Cannot redirect the page by passing values

Hi,
I need to auto-redirect a page depending on the a ID number in the address bar. When I run this code, It is giving following exception           
            string temp = Request.Url.ToString();
            string subTemp = temp.Substring(temp.IndexOf("ID="));
            temp = subTemp.Remove(subTemp.IndexOf("&"));
            subTemp = temp.Substring((temp.IndexOf("=") + 1));

            Response.Redirect("http://Share1/ncr/Default.aspx?ID=" + subTemp);

Server Error in '/' Application. StartIndex cannot be less th ...