jQuery/AJAX, retrieving a string that my method returns

I have this code-behind:

我有这个代码隐藏:

    [WebMethod]
    [ScriptMethod(UseHttpGet=true)]
    public string GetMessage() {
        XmlTextReader reader = new XmlTextReader (Global.sAppPath + "/alt/importantMsg.xml");

        string message = null;

        while (reader.Read()) {
            if (reader.IsStartElement ()) {
                switch (reader.Name.ToString ()) {

                case "Message":
                    message = reader.ReadString();
                    break;
                }
            } 
        }

        return message;
    }
    [We