eSystem.Xml.XmlException: Root element is missing.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
   at System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace)
   at System.Xml.XmlDocument.Load(XmlReader reader)
   at System.Xml.XmlDocument.LoadXml(String xml)
   at DocAvePreview.Common.XmlUtility.ToObject(String xml, Type type)
   at DocAvePreview.Common.XmlUtility.ToObject[T](String xml)
   at DocAvePreview.GUI.Ajax.AjaxCommand.GetInstance(String ajaxCmdString)
   at DocAvePreview.GUI.Ajax.AjaxHandler.GetCallbackResult()
   at DocAvePreview.GUI.WebHandlerBase.ProcessRequest(HttpContext context)