Django Rest framework 405 Method Not Allowed?

class ConfirmCourierAPIView(views.APIView):
    serializer_class = ConfirmCourierSerializer

    def post(self, request, delivery_id, *args, **kwargs):
        delivery = get_object_or_404(Delivery, id=delivery_id)
        conf_delivery = get_object_or_404(CourierPropouse, delivery=delivery)
        if conf_delivery.final_price:
            final_price = conf_delivery.final_price
        else:
            final_price = delivery.price
        serializer = self.get_serializer_class()(data=request.data)
        if serializer.is_valid() and \
                delivery.customer == request.user and \
                delivery.status == 'open':
            serializer.save(delivery=delivery, final_price=final_price)
            delivery.status = 'closed'
            delivery.save()
            return Response(status=status.HTTP_201_CREATED)
        return Response(status=status.HTTP_400_BAD_REQUEST)