XMLDOCUMENT Web Service Returns XMLNODE

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Xml)]
public XmlDocument SearchBySpot(string spot)
{
    XmlDocument doc = new XmlDocument();
    try {
        DataTable result = new DataTable();
        result.TableName = "Location";
        string con = "myconnstring";
        using (SqlConnection connection = new SqlConnection(con))
        {

            SqlCommand cmd = new SqlCommand("GetByspot", connection);
            cmd.CommandType = CommandType.StoredProcedure;
            SqlParameter parameter = new SqlParameter("@spot", spot);
            cmd.Parameters.Add(parameter);
            connection.Open();
            SqlDataAdapter adapter = new SqlDataAdapter(cmd);
            SqlDataReader reader = cmd.ExecuteReader();
            result.Load(reader);



            DataSet ds = new DataSet();
            adapter.Fill(ds, "Location");
            string strXML = ds.GetXml();

            doc.LoadXml(strXML);



            connection.Close();



        }

    }
    catch (Exception ex)
    {

    }
    return doc;
}