asp.net WebApi returns html page

asp.net WebApi returns html page

        public HttpResponseMessage Get(string id)
        {
            if (id.Contains("OID="))
            {
                id = id.Replace("OID=", "");
            }
            else if (id.Contains("oid="))
            {
                id = id.Replace("oid=", "");
            }
            else
            {
                id = "Not Found!";
            }
            string html = getHtml(id);
            var result = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(html, Encoding.UTF8, "text/html")
            };
            return result;
        }