Save Editor.Content To Xml Works On Local Machine But Not On Server?

I have html editor on page, ajax 3.5. I can save Editor.Content to xml file without problem, after I publish to server machine, It refused to work for me.

my page directive set to ValidateRequest = false and EnableEvenValidate = false and AutoEventWireUp = false, no UpdatePanel used around Editor and update button. on code behind which is button click event.

Dim docInfo.Load(Server.MapPath(xmlInfoFilePath))
docInfo As
New System.Xml.XmlDocument()
Dim ndInfo As System.Xml.XmlNode
ndInfo = docInfo.SelectSingleNode("/info/business[@user='" & User.Identity.Name &
"']")
If ndInfo IsNot
Nothing Then
ndInfo.Attributes("description").Value = Editor.Content
docInfo.Save(Server.MapPath(xmlInfoFilePath))
End If
docInfo = Nothing

This button click generate an error on server side. I guess the problem Editor.Content have hidden tags, the server refuse to accept, but what is real problem.