htmlfile: 未知的运行时错误

运行一下代码提示如题！请高手支招！
主要代码
[Ajax.AjaxMethod(HttpSessionStateRequirement.Read)]
 public string GetNewMsgString()
 {
 string strMsgHTML = string.Empty;
 try
 {
 m_NewUser = Session["u"].ToString();
 SqlConnection m_sqlcon = db.GetSQLCon();
 SqlCommand m_cmd = m_sqlcon.CreateCommand();
 m_cmd.CommandType = CommandType.StoredProcedure;
 m_cmd.CommandText = "GetNewMsg";
 m_cmd.Parameters.AddWithValue("@username", m_NewUser);
 m_sqlcon.Open();
 using (SqlDataReader m_dr = m_cmd.ExecuteReader())
 {
 while (m_dr.Read())
 {
 string fd1 = m_dr.GetString(1);
 if (fd1 != "")
 {
 string fd2 = m_dr.GetString(2);
 string fd3 = m_dr.GetString(3);
 string fd4 = m_dr.GetString(4);
 string fd5 = m_dr.GetString(5);
 strMsgHTML += string.Format(
 @"{1} {2} {3} {4} {5} ",
 fd5,
 fd1,
 TestIsPublic(false),
 TestYourself(fd2),
 fd4,
 Replace_GTLT(fd3));
 }
 else
 {
 strMsgHTML += string.Format(
 @"{1}",
 m_dr.GetString(3));
 }
 }
 }
 m_sqlcon.Close();
 SetMsgPos();
 return strMsgHTML;
 }
 catch (Exception ex)
 {
 return strMsgHTML;
 }

 }

 function send() {
 var txtContent = document.all("chatcontent").value;
 if (txtContent == "") return;
 var user_to = document.all("userlist").value;
 var textcolor = document.all("textcolor").value;
 var expression = document.all("expression").value;
 var isPublic = !(document.all("isSecret").checked);
 ChatRoom.SendMsg(txtContent, user_to, textcolor, expression, isPublic);
 var div = document.all("chatcontent");
 alert(ChatRoom.GetNewMsgString().value);
 div.innerHTML = ChatRoom.GetNewMsgString().value + div.innerHTML;
 document.all("chatcontent").value = "";
 refresh_chatcontent();
 }
 function refresh_chatcontent() {
 var div = document.all("txtNews");
 var strNewMsg = ChatRoom.GetNewMsgString().value;
 if (strNewMsg != null && strNewMsg != "")
 div.innerHTML = strNewMsg + div.innerHTML;
 window.setTimeout(refresh_chatcontent, 10000);
 } --------------------编程问答-------------------- 看你有几个赋给DIV。。innerhtml的代码

form标签中有innerHTML代码，

把innerHTML的div放在form标签，body标签之内
--------------------编程问答--------------------

补充：.NET技术 ,  ASP.NET