Call method of Abstract class from Child class

Question

I want to modify setDateRange method in Mage_Reports_Model_Resource_Report_Collection_Abstract class. I know it's not possible to override an Abstract class, so I searched for its child and it was another abstract: Mage_Sales_Model_Resource_Report_Collection_Abstract. I searched again and I found Mage_Sales_Model_Resource_Report_Order_Collection. I overrode it and modified the method. So I have this code:

class Namespace_Module_Model_Sales_Resource_Report_Order_Collection
extends Mage_Sales_Model_Resource_Report_Order_Collection
{
    /**
     * Set date range
     *
     * @param mixed $from
     * @param mixed $to
     * @return Mage_Sales_Model_Resource_Report_Collection_Abstract
     */
    public function setDateRange($from = null, $to = null)
    {
        var_dump('modified!');
    }
}

Problem is my method did not call. I wrote a script to make sure that Magento knows about my class:

require 'app/Mage.php';

Mage::app();

$c = Mage::getModel('sales/resource_report_order_collection');

var_dump(get_class($c)); // Output: Namespace_Module_Model_Sales_Resource_Report_Order_Collection
var_dump(method_exists($c, 'setDateRange')); // Output: true
var_dump($c->setDateRange()); // Output: modified!

First, I want to know why Magento never calls my method? And second, how should I modify that method?

Update:

I have a long config.xml file and I don't think it's necessary to paste it here. But here's models part:

<models>
  <namespace_module>
    <class>Namespace_Module_Model</class>
  </namespace_module>
  <sales>
    <rewrite>
        <resource_report_order_collection>Namespace_Module_Model_Sales_Resource_Report_Order_Collection</resource_report_order_collection>
    </rewrite>
  </sales>
  <eav>
    <rewrite>
      <entity_attribute_backend_datetime>Namespace_Module_Model_Eav_Entity_Attribute_Backend_Datetime</entity_attribute_backend_datetime>
    </rewrite>
  </eav>
  <catalog>
    <rewrite>
      <product_attribute_backend_startdate>Namespace_Module_Model_Catalog_Product_Attribute_Backend_Startdate</product_attribute_backend_startdate>
      <product_attribute_backend_startdate_specialprice>Namespace_Module_Model_Catalog_Product_Attribute_Backend_Startdate_Specialprice</product_attribute_backend_startdate_specialprice>
    </rewrite>
  </catalog>
</models>

Answer 1

You are rewrite the resource model. So you have to rewrite like below.

<models>
   <sales_resource> 
      <rewrite>
          <report_order_collection>Namespace_Module_Model_Sales_Resource_Report_Order_Collection</report_order_collection>
      </rewrite> 
    </sales_resource>
</models>