Alternative way to do it.
Using a DataSet will automatically give you the table structure.
XDocument xDoc = XDocument.Load('your file name');
XElement xeMsg = xDoc.Element(XName.Get("MSG", "http://tempuri.org/"));
XElement xeRd = xeMsg.Element(XName.Get("RD", "http://tempuri.org/"));
DataSet ds = new DataSet();
ds.ReadXml(xeRd.CreateReader());
if (ds.Tables["Table"].Rows.Count == 1)
{
DataRow dr = ds.Tables["Table"].Rows[0];
string userName = dr["USERNAME"].ToString();
string email = dr["EMAIL"].ToString();
}