我尝试在Magento（1.5.1.0）的后端创建一个订单。
下面是一些代码：

// Get the product id stored in the optionValue of the widget
        $productId = $order['customIdNumber'];

        // Load the product
        $product = Mage::getModel('catalog/product')->load($productId);

        // Check whether the product could be loaded
        if($product->getId())
        {
            // Get the customer model
            $customer = Mage::getModel('customer/customer');

            // Set the website id associated with the customer
            $customer->setWebsiteId(Mage::app()->getWebsite()->getId());

            // Try to load the customer by email
            $customer->loadByEmail($order['personAddresses'][0]['email']);

            // Check whether the customer not exists
            if(!$customer->getId())
            {
                // Create the customer
                $customer->setEmail($order['personAddresses'][0]['email']);
                $customer->setFirstname($order['personAddresses'][0]['firstName']);
                $customer->setLastname($order['personAddresses'][0]['lastName']);
                $customer->save();
            }

            // Set the esstial order data
            $orderData = array(
                'currency' => $order['currencyCode'],
                'account'  => array(
                    'group_id' => Mage_Customer_Model_Group::NOT_LOGGED_IN_ID,
                    'email'    => $order['personAddresses'][0]['email']
                ),
                'billing_address' => 
                    'firstname'  => $order['personAddresses'][0]['firstName'],
                    'lastname'   => $order['personAddresses'][0]['lastName'],
                    'street'     => $order['personAddresses'][0]['street'],
                    'city'       => $order['personAddresses'][0]['city'],
                    'country_id' => $order['personAddresses'][0]['country'],
                    'region_id'  => 'BW',
                    'postcode'   => $order['personAddresses'][0]['postalCode'],
                    'telephone'  => '0123456789',
                ),
                'comment' => array(
                    'customer_note' => "[Order has been created by the sellaround widget module]\nCustomer message:\n".
                                       $order['personAddresses'][0]['message']
                ),
                'send_confirmation' => false // does that something?
            );

            // Set the shipping address to the billing address
            $orderData['shipping_address'] = $orderData['billing_address'];

            // Set the payment method
            $paymentMethod = 'checkmo';

            // Set the shipping method
            $shippingMethod = 'flatrate_flatrate';

            // Get the backend quote session
            $quoteSession = Mage::getSingleton('adminhtml/session_quote');

            // Set the session store id
            $quoteSession->setStoreId(Mage::app()->getStore('default')->getId());

            // Set the session customer id
            $quoteSession->setCustomerId($customer->getId());

            // Get the backend order create model
            $orderCreate = Mage::getSingleton('adminhtml/sales_order_create');

            // Import the data
            $orderCreate->importPostData($orderData);

            // Calculate the shipping rates
            $orderCreate->collectShippingRates();

            // Set the shipping method
            $orderCreate->setPaymentMethod($paymentMethod);

            // Set the payment method to the payment instance
            $orderCreate->getQuote()->getPayment()->addData(array('method' => $paymentMethod));

            // Set the shipping method
            $orderCreate->setShippingMethod($shippingMethod);

            // Set the quote shipping address shipping method
            $orderCreate->getQuote()->getShippingAddress()->setShippingMethod($shippingMethod);

            // Add the product
            $orderCreate->addProducts(array($product->getId() => array('qty' => 0)));

            // Initialize data for price rules
            $orderCreate->initRuleData();

            // Save the quote
            $orderCreate->saveQuote(); // neccessary?

            // Create the order
            $order = $orderCreate->createOrder();
        }

我总是在第293行的Mage_Sales_Model_Service_Quote::_validate中得到异常“请指定一种运送方法。”
异常周围的行的代码：

$method= $address->getShippingMethod();
    $rate  = $address->getShippingRateByCode($method);
    if (!$this->getQuote()->isVirtual() && (!$method || !$rate)) {
        Mage::throwException($helper->__('Please specify a shipping method.'));
    }

有人知道为什么我会得到这个错误吗？是因为无法加载费率吗？（产品不是虚拟的）