System.InvalidOperationException: Invalid Attempt To MetaData When Reader Is Closed

 I am getting this exception sporadically in a certain block of code (it usually works):

"System.InvalidOperationException: Invalid attempt to MetaData when reader is closed"The code is below:

cmd.CommandText = "[dbo].CountryGetList";
cmd.CommandType = CommandType.StoredProcedure;

IDataReader rdr = cmd.ExecuteReader();
List countries = new List();

...

while (rdr.Read())
{

//do stuff
                  
CountryID = (Guid)rdr["CountryID"];
 //blows up on the next line
cty.Name = (string)rdr["Name"];
            }

}


rdr.Close();

Any ideas!?