title: How override model in Magento correctly?
body: <p>guys.</p>
  
  <p>I need to override 2 functions in different classes (CatalogSearch/Layer.php and CatalogSearch/Mysql4/Fulltext/Collection.php). So, I have a config file:</p>
  
  <pre><code>&lt;config&gt;
      &lt;modules&gt;
          &lt;my_modulename&gt;
              &lt;version&gt;0.1&lt;/version&gt;
          &lt;/my_modulename&gt;
      &lt;/modules&gt;
      &lt;global&gt;
          &lt;models&gt;
              &lt;catalogsearch&gt;
                  &lt;rewrite&gt;
                      &lt;layer&gt;My_Modulename_Model_CatalogSearch_Layer&lt;/layer&gt;
  &lt;mysql4_fulltext_collection&gt;My_Modulename_Model_CatalogSearch_Mysql4_Fulltext_Collection &lt;/mysql4_fulltext_collection&gt;
                  &lt;/rewrite&gt;
              &lt;/catalogsearch&gt;
          &lt;/models&gt;
      &lt;/global&gt;
  &lt;/config&gt;
  </code></pre>
  
  <p>Hence, Layer.php has been overridden correctly , but Collection.php hasn't - '/local/My/Modulename/Model/CatalogSearch/Mysql4/Fulltext/Collection.php' was not even included. Why?  </p>
  
  <p>Thank you for any help.</p>