如何在magento 1.8.1中添加产品图片销售订单网格？

Question

如何在magento 1.8.1中添加产品图片销售订单网格？
我试过下面的代码，但显示空白图像，我想在这里销售的产品？

public function callback_thumbnail($value, $row, $column, $isExport) { 
    $product_id = $value; 
    $product = Mage::getModel('catalog/product')->load($product_id); 
    $url = Mage::helper('catalog/image')->init($product,  'thumbnail')>resize(70,70); 
    return "<img src='$url' />"; 
    } 
    $this->addColumn('entity_id', array(
     'header' => Mage::helper('catalog')->__('Thumbnail'), 
      'index' => 'entity_id', 
      'frame_callback' => array($this, 'callback_thumbnail') 
     )); 

Answer 1

我解决了这个问题，这个扩展 http://www.magentocommerce.com/magento-connect/advanced-ordergrid-with-images.html