At the time the horses reach the finish line, the placing judges shall occupy the stand provided for them and shall determine the order of finish. In such determination, a horse whose nose shall have reached the finish line shall be deemed ahead of all horses whose noses shall not have reached the finish line. The placing judges shall announce their decision as to the order of finish, and their decisions shall be final unless objection to any horse placed in the first four positions be raised and sustained. However, the placing judges may, with the concurrence or at the direction of the stewards, correct any mistake in the order of finish announced. In the absence of any objections, or upon decisions having been reached with relation to any objections raised and any changes in the order of finish required by such decisions having been made, the placing judges shall cause the sign "official" to be displayed; and no ruling of the placing judges or stewards thereafter made shall have any bearing with relation to the payment of winning parimutuel tickets.