title: Can not override Sales Resouce Model Collection class
body: <p>I am trying to override <strong>Mage_Sales_Model_Resource_Order_Collection</strong></p>
  
  <p>My custom module's config:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  
  
  &lt;config&gt;
      &lt;modules&gt;
          &lt;Abc_Salesextend&gt;
              &lt;version&gt;0.1.0&lt;/version&gt;
          &lt;/Abc_Salesextend&gt;
      &lt;/modules&gt;
  
      &lt;global&gt;       
          &lt;blocks&gt;
              &lt;salesextend&gt;
                  &lt;class&gt;Abc_Salesextend_Block&lt;/class&gt;   
              &lt;/salesextend&gt;  
  
              &lt;adminhtml&gt;
                  &lt;rewrite&gt;
                      &lt;sales_order_grid&gt;Abc_Salesextend_Block_Sales_Order_Grid&lt;/sales_order_grid&gt;
                  &lt;/rewrite&gt;                
              &lt;/adminhtml&gt;    
          &lt;/blocks&gt;
  
          &lt;models&gt;
              &lt;salesextend&gt;
                  &lt;class&gt;Abc_Salesextend_Model&lt;/class&gt;   
                  &lt;resourceModel&gt;salesextend_resource&lt;/resourceModel&gt; 
              &lt;/salesextend&gt;
  
              &lt;salesextend_resource&gt;
                  &lt;class&gt;Abc_Salesextend_Model_Resource&lt;/class&gt;
              &lt;/salesextend_resource&gt;
  
              &lt;!-- HERE is i am trying to override--&gt;
  
              &lt;sales_resource&gt;
                  &lt;rewrite&gt;
  
                      &lt;order_collection&gt;Abc_Salesextend_Model_Resource_Order_Collection&lt;/order_collection&gt;
  
                  &lt;/rewrite&gt;                
              &lt;/sales_resource&gt;    
          &lt;/models&gt;
      &lt;/global&gt;
  
  &lt;/config&gt;
  </code></pre>
  
  <p>It's not giving me any kind of error even if I place the wrong custom class name. So it's not finding my custom class. </p>
  
  <p>Please help </p>