Magento 1.8 – Troubleshoot Sales Order Event Observer Problems

I've got an observer that is registered and firing on the sales_order_place_after event. However when I try and call getAllVisibleItems() on the order the entire process errors out.
I've tested the code outside of placing an order, so I didn't have to complete the checkout process each time, by using

$order->Mage::getModel('sales/order')->loadByIncrementId($ordernumber);

My event Observer is as follows:

class Shopatron_OrderExport_Model_Observer
{
    public function exportOrder(Varien_Event_Observer $observer)
    {
            Mage::log('Shopaton Order Observer', null, 'Shopatron.log');
            $order = $observer->getEvent()->getOrder();

            $ShopatronExport=Mage::getModel('shopatron_orderexport/export');
            $ShopatronExport->exportOrder($order);

            return true;
    }
}

And the Export Model is:

class Shopatron_OrderExport_Model_Export
{
    public function exportOrder($order)
    {       
            Mage::log('Shopaton Order exportOrder', null, 'Shopatron.log');
            $dirPath = Mage::getBaseDir('var') . DS . 'export';

            if (!is_dir($dirPath))
            {
                    mkdir($dirPath, 0777, true);
            }
            $customerIP = Mage::helper('core/http')->getRemoteAddr(true);

            //Getting the Proper 2 Character State
            $regionModel = Mage::getSingleton('directory/region');
            $regionModel->load($order->getShippingAddress()->getRegionId());
            $sstate_code = $regionModel->getCode();
            $regionModel->load($order->getBillingAddress()->getRegionId());
            $bstate_code = $regionModel->getCode();
            Mage::log($bstate_code, null, 'Shopatron.log');
            Mage::log($sstate_code, null, 'Shopatron.log');
            $data = array('OrderID'=>$order->getIncrementId(), 
                    'Email'=>$order->getData('customer_email'), 
                    'CustomerIP'=>$customerIP,
                    'ShipMethod' =>$order->getData('shipping_method'),
                    'ShippingPhone' =>$order->getShippingAddress()->getData('telephone'),
                    'ShippingFirstName'=>$order->getShippingAddress()->getFirstname(),
                    'ShippingLastName' => $order->getShippingAddress()->getLastname(),
                    'ShippingStreet' => $order->getShippingAddress()->getStreet(),
                    'ShippingCity' => $order->getShippingAddress()->getCity(),
                    'ShippingState' =>  $sstate_code,
                    'ShippingCountry' => $order->getShippingAddress()->getCountryId(),
                    'ShippingZip' => substr($order->getShippingAddress()->getPostcode(),0,5),
                    'BillingPhone' => $order->getBillingAddress()->getData('telephone'),
                    'BillingFirstName' => $order->getBillingAddress()->getFirstname(),
                    'BillingLastName' => $order->getBillingAddress()->getLastname(),
                    'BillingStreet' => $order->getBillingAddress()->getStreet(),
                    'BillingCity' => $order->getBillingAddress()->getcity(),
                    'BillingState' => $bstate_code,
                    'BillingCountry' => $order->getBillingAddress()->getCountryId(),
                    'BillingZip' => substr($order->getBillingAddress()->getPostcode(),0,5),
                    //Why can't I call getAllVisibleItems?
                    'Items' => $order->getAllVisibleItems()

            );

            try{
              $data['Items']=createOrderItems( $order->getIncrementId());
            } catch(Exception $e){
              Mage::log($e->getMessage(), null, 'system.log');
              //Nothing shows up in the log to help troubleshoot
            }
            //$xstrout = toXmlRpc($data);
            /*file_put_contents(
                    $dirPath. DS .$data['OrderID'].'.xml22',
                    print "<PRE>" . htmlentities ( $xstrout ) . "</PRE>", 
                    FILE_APPEND
            );*/
            //sendMsg($xstrout);
            return true;
    }

    public function createOrderItems($orderId)
    {
            Mage::log('Shopatron Order createOrderItems', null, 'Shopatron.log');
            $order=Mage::getModel('sales/order')->loadByIncrementId($orderId);
            $items=$order->getAllVisibleItems();
            $i=0;
            $itemcount=count($items);
            foreach ($items as $itemId => $item)
            {
                    $IO[$itemId]['name']=$item->getName();
                    $IO[$itemId]['price']=$item->getPrice();
                    $IO[$itemId]['sku']=$item->getSku();
                    $IO[$itemId]['id']=$item->getProductId();
                    $IO[$itemId]['upc']=getUpcFromSku($item->getSku());
                    $IO[$itemId]['qty']=$item->getQtyOrdered(); //$item->getQtyToInvoice();
                    //$IO[$itemId]['options']=createOptionsArray($item->getProductOptions(), $itemId);
                    if($itemcount>1)
                    {
                            $IO[$itemId]['shipping']=$order->getData('shipping_amount')/$itemcount;
                            $IO[$itemId]['tax'] = $order->getData('tax_amount')/$itemcount;
                    }
                    elseif($itemcount == 1)
                    {
                            $IO[$itemId]['shipping']=$order->getData('shipping_amount');
                            $IO[$itemId]['tax'] = $order->getData('tax_amount');
                    }       
                    $i++;
            }
            return $IO;
    }
}

Any help would be much appreciated. Thanks!