ASP.NET AJAX调用不成功的有关问题

<script type="text/javascript" language="javascript">        function submitSay() {            var content = $("#saycontent")[0].value;            if (content.length == 0) {                return;            }            $.ajax({                type: "POST",                contentType: "application/json;charset=utf-8",                url: "LogIndex.aspx/SubmitDiscuss",                data: "{content:\"" + content + "\"}",                dataType: "json",                success: function () {                    alert("添加成功！")                },                error: function (XmlHttpRequest, textStatus, errorThrown) {                    //alert(XmlHttpRequest.responseText)                    document.write(XmlHttpRequest.responseText);                }            });        }    </script>

        [WebMethod]        public void SubmitDiscuss(string content)        {            LogContext model = new LogContext            {                ID = Guid.NewGuid().ToString(),                UserID = "96ecdc8b-4cd1-4f44-b93e-d473a4b59128",                LogText = content,                LogTitle = "说说",                LogType = 2,                PubDate = DateTime.Now            };            business.AddLog(model);        }