"No data exists for the row/column." exception message throwing

While executing the following code in Asp.net with C#,getting an exception like "No data exists for the row/column."

OdbcConnection DbConnection = new OdbcConnection(ConfigurationManager.AppSettings["ConnectionStr"]);
DbConnection.Close();
string cmdText = "SELECT Team_ID FROM team_details WHERE Team_Code=?";
OdbcCommand cmd = new OdbcCommand(cmdText, DbConnection);

cmd.Parameters.Add("?Code", OdbcType.VarChar).Value = tbCode.Text; DbConnection.Open(); OdbcDataReader DR = cmd.ExecuteReader();

DR.Read();
if (DR.GetValue(0) != DBNull.Value)
{ args.IsValid = false; } else { args.IsValid = true; } DbConnection.Close();

I'm using Visual Studio 2008 and MySQL. and  MySql ODBC connector 5.1 and MDAC2.8.

Please guide me how to resolve this.