magento override block function not calling

Question

I override my sales order view info but the function not working.

config.xml

<global>
<adminhtml>
<rewrite> 
 <sales_order_view_info>MPS_Delivery_Block_Sales_Order_View_Info</sales_order_view_info>
</rewrite>
</adminhtml>
</global>

info.php

class MPS_Delivery_Block_Sales_Order_View_Info extends Mage_Adminhtml_Block_Sales_Order_View_Info
{
    public function getMyTest(){

        return "Test";
    }
}

I called in my template in this <?php echo $this->getMyTest();?>

What mistake i made here

Answer 1

I think you have error in your config.xml

Your xml structure is not correct. You need to add your rewrite code in <block> tag and not in <config> tag.

Try adding below inside your <config> tag.

<blocks>
    <delivery>
    <class>MPS_Delivery_Block</class>
    </delivery>
    <adminhtml>
        <rewrite>
            <sales_order_view_info>MPS_Delivery_Block_Adminhtml_Sales_Order_View_Info</sales_order_view_info>
        </rewrite>
    </adminhtml>
</blocks>

Also the file you have created is in wrong location. Create your Info.php at app\code\YOUR_CODEPOOL\MPS\Delivery\Block\Adminhtml\Sales\Order\View\Info.php

Add your code

<?php
class MPS_Delivery_Block_Adminhtml_Sales_Order_View_Info extends Mage_Adminhtml_Block_Sales_Order_View_Info
{
    public function getMyTest(){

        return "Test";
    }
}

Answer 2

In config.xml you have to add tag <blocks> like:

<global><blocks><adminhtml><rewrite>

And Info.php file should have to under Adminhtml folder like: Block/ Adminhtml /Sales/Order/View/Info.php