Magento无法通过OrderController创建MassAction.怎么了

我对这段代码不起作用感到有点恼火。有什么建议吗？

新创建的massAction没有找到，而是一个404？

config.xml:

<?xml version="1.0"?>
<config>
    <modules>
        <SNH_ShipMailInvoice>
            <version>0.1.0</version>
        </SNH_ShipMailInvoice>
    </modules>
    <global>
        <events>
            <!-- Event to attach observer to -->
            <core_block_abstract_to_html_before>
                <observers>
                    <SNH_ShipMailInvoice>
                        <type>singleton</type>
                        <!-- Observer location (e.g. SW/GridExample/Model) -->
                        <class>SNH_ShipMailInvoice_Model_Observer</class>
                        <!-- Function to call -->
                        <method>addMassAction</method>
                    </SNH_ShipMailInvoice>
                </observers>
            </core_block_abstract_to_html_before>
        </events>
    </global>
    <admin>
        <routers>
            <adminhtml>
                <args>
                    <modules>
                        <!-- Override Adminhtml module here. -->
                        <SNH_ShipMailInvoice before="Mage_Adminhtml">SNH_ShipMailInvoice</SNH_ShipMailInvoice>
                    </modules>
                </args>
            </adminhtml>
        </routers>
    </admin>
</config>

Observer.php工作正常，并显示选项（如下）：

<?php
class SNH_ShipMailInvoice_Model_Observer
{
    public function addMassAction($observer)
    {
        $block = $observer->getEvent()->getBlock();
        // Check if this block is a MassAction block
        if ($block instanceof Mage_Adminhtml_Block_Widget_Grid_Massaction) {
            // Check if we're dealing with the Orders grid
            if ($block->getParentBlock() instanceof Mage_Adminhtml_Block_Sales_Order_Grid) {
                // The first parameter has to be unique, or you'll overwrite the old action.
                $block->addItem('ship_mail_invoice', array(
                        'label' => Mage::helper('sales')->__('Ship, Mail and Invoice'),
                        'url' => $block->getUrl('*/*/shipmailinvoice'),
                    )
                );
            }
        }
    }

现在，当我选择新创建的选项时，我收到一个404未找到的错误。URL类似于admin/sales_order/shipmailinvoice/key/。

OrderController.php文件位于SNH/ShipMailInvoice/controllers/Adminhtml/Sales/OrderController.php:中

require_once('Mage/Adminhtml/controllers/Sales/OrderController.php');
class SNH_ShipMailInvoice_Adminhtml_Sales_OrderController extends Mage_Adminhtml_Sales_OrderController
{
    public function shipmailinvoiceAction()
    {
        // This should be called when the url has the pattern '*/*/attack' (as it does
        // when displaying my custom tab) however clicking this tab gives a 404.
        die('<h1>attackAction()</h1>');
    }
}