XML Error in Asp.Net

I am trying to read XML file by dataset but getting error(""Cannot add a nested relation or an element column to a table containing a SimpleContent column."") . 

Example:

<?xml version='1.0' encoding='utf-8'?><Employees><Name><EmployeeName>
     ABCD </EmployeeName></Name><Details><ID>1</Details><FullDetails><FirstName>John</FirstName><LastName>Qwerty</LastName></FullDetails></Details></Employees>

 ds = new DataSet();
 ds.ReadXml(Server.MapPath(xmlPath.ToString() + "/Result.xml"));

Please tell me