Magento在mage_tax模块中重写或禁用事件观察器

Question

我试图重写观察者类，但它无法正常工作。所以我决定禁用那个观察者并创建我自己的观察者。以下是我的代码，

<?xml version="1.0"?>
<config>
    <modules>
        <Test_Taxprice>
            <version>0.1.0</version>
        </Test_Taxprice>
    </modules>
    <global>
        <helpers>
            <taxprice>
                <class>Test_Taxprice_Helper</class>
            </taxprice>
        </helpers>
        <models>
            <taxprice>
                <class>Test_Taxprice_Model</class>
                <resourceModel>taxprice_mysql4</resourceModel>
            </taxprice>
        </models>
        <events>
            <sales_order_save_after> <!-- identifier of the event we want to catch -->
                <observers>
                <mage_tax>
                <type>disabled</type>
                </mage_tax>
                    <sales_order_save_after_handler> <!-- identifier of the event handler -->
                        <type>model</type> <!-- class method call type; valid are model, object and singleton -->
                        <class>taxprice/observer</class> <!-- observers class alias -->
                        <method>salesEventOrderAfterSave</method>  <!-- observer's method to be called -->
                        <args></args> <!-- additional arguments passed to observer -->
                    </sales_order_save_after_handler>
                </observers>
            </sales_order_save_after>
        </events>
    </global>
</config>

在这里，我尝试禁用该观察者并触发我自己的观察者，但它无法正常工作..提示？