System.InvalidOperationException: This document already has a 'DocumentElement' node.
   at System.Xml.XmlDocument.IsValidChildType(XmlNodeType type)
   at System.Xml.XmlNode.AppendChild(XmlNode newChild)
   at tfox.CommonLibrary.CommonClass.GetSysXmlNode(String NodeName)
   at tfox.fenzhan.NGenerateSub.GetData(String entity, String filter)
   at tfox.fenzhan.NGenerateSub.BindData(Match match, StringBuilder sb)
   at tfox.fenzhan.NGenerateSub.BindData(StringBuilder sb, String rootPath, String template)
   at tfox.fenzhan.NGenerateSub.GenerateHead(String rootPath, String template)
   at tfox.fenzhan.NGenerateSub.BindFixData(StringBuilder sb, String rootPath, String template)
   at tfox.fenzhan.NGenerateSub.BindData(StringBuilder sb, String rootPath, String template)
   at tfox.fenzhan.NGenerateSub.GenerateProList(String rootPath, String template, String typeid1, String id, String city, String py, String page)