Magento: Display custom product attribute in admin Items ordered block

I am trying to display my custom attribute value on admin order - Items Ordered block. It will show points earned for each product just like as it shows SKU and other information. The attribute value is saved in sales_flat_quote_item and sales_flat_order_item tables.

Namespace/Modulename/Block/Adminhtml/Sales/Order/View/Items/Renderer/Default.phtml

<?php

class Namespace_Modulename_Block_Adminhtml_Sales_Order_View_Items_Renderer_Default extends Mage_Adminhtml_Block_Sales_Order_View_Items_Renderer_Default
{

}

?>

app/design/adminhtml/design/design/layout/namespace/modulename.xml

<adminhtml_sales_order_view>
        <reference name="order_items">
            <action method="addItemRender"><type>default</type>
                <block>sales/order_item_renderer_default</block>
                <template>namespace/modulename/sales/order/items/renderer/default.phtml</template>
            </action>
        </reference>
</adminhtml_sales_order_view>

app/design/adminhtml/default/default/template/namespace/modulename/sales/order/view/items/rederer/default.phtml

    <?php $finalPointsEarned = ($_item->getCustomerProductPoints() * $_item->getQtyOrdered()); ?>
    <div class="product-cart-sku">
        <span style="color: #d4af37; font-weight: bold;"><?php echo $this->__('Points Earned:'); ?>
            <?php echo $finalPointsEarned ?>
        </span>
    </div>

Executing above code gives below exception

Invalid method Mage_Sales_Block_Order_Item_Renderer_Default::addColumnRender(Array
(
    [0] => qty
    [1] => adminhtml/sales_items_column_qty
    [2] => sales/items/column/qty.phtml
)
)

Changing <adminhtml_sales_order_view> to <sales_order_view> does not give any output and custom prod attribute is not displayed.

Attempt Two:

<adminhtml_sales_order_view>
        <reference name="order_items"> 
            <action method="addColumnRender">
                <column>NORTH FACE</column>
                <block>adminhtml/sales_items_column_name</block>
                <template>modulename/sales/items/column/name.phtml</template>
            </action>
        </reference> 
</adminhtml_sales_order_view>

added my custom code in name.phtml, still no output.

1. How do I display the value of custom product attribute on Items ordered block ?
2. How do I display the same value of admin Invoice order details page ?
3. Is above, the best practice/method to display custom attribute on admin order/invoice/refund pages just like it displays SKU, Size and other values ?

The easiest and most efficient way is to create a custom theme for a store admin, copy-paste the requested template in there and rewrite the output the way you want to have it.

Thus you will be able to fully customize it. Also, this approach will lower the risk of getting errors and provide you with the ability to customize any templates (including invoices, credit memos, etc.)

Have a look:

• Set a custom theme: (can be done in app/etc/local xml or in your extension config settings):

• Copy the template you need:

• Adjust it as you need:

• And get the result you want:

Note that the custom attribute is usually entered via get method. If you are having any trouble with that, just check if it exists for the chosen item in the database. In the sales_flat_order_item table find all the items related to the chosen order and make sure that it has the value, different from null. This is how it worked in my case: