DataSet.ReadXML报错,该怎么处理

DataSet.ReadXML报错

C# code

  public static DataSet ConvertXmlToDataSet(Stream XMldata)        {            XmlTextReader xmlReader = null;            StringReader reader = null;            try            {                DataSet xmlDs = new DataSet();               [color=#FF0000] xmlDs.ReadXml(XMldata);[/color]                return xmlDs;            }            catch (Exception ex)            {                return null;            }}