Visual CSharp .NET - Store procedure y odbc

PROCEDURE SP_LISTADO_ZONA (ve_cod_zona in number, vs_dato_zona out varchar2) is

    begin

      SELECT des_localidad

      into vs_dato_zona

      from Vt_Zonas WHERE Cod_Zona = ve_cod_zona;

    end SP_LISTADO_ZONA;

public List<string> CargarZonaDespacho()

        {

            List<string> prueba = new List<string>();

            using (OdbcConnection connection = new OdbcConnection())

            {

                connection.ConnectionString = ConfigurationManager.ConnectionStrings[EUsuario.CADENA_BASE].ConnectionString;

                using(OdbcCommand comand = new OdbcCommand())

               	{

                    comand.Connection = connection;

                    comand.CommandType = CommandType.StoredProcedure;

                    comand.CommandText = ("{CALL PKG_PMVENTAS.SP_LISTADO_ZONA (?)}");

                    comand.Parameters.Add("ve_cod_zona", OdbcType.Int).Value = 0;

                    connection.Open();

                    OdbcDataReader reader = comand.ExecuteReader();

                    while (reader.Read())

                    {

                        prueba.Add(reader[0].ToString());

                    }

	            }

                connection.Close();

                return prueba;

            }

        }