MODX shk set status order

$modelpath = $modx->getOption('core_path') . 'components/shopkeeper3/model/';
$modx->addPackage( 'shopkeeper3', $modelpath );

$order = $modx->getObject('shk_order', 18);
            if (!$order) {
                die('no shk_order object found');
            }

            $order->set('status', 6);
            $order->save();