title: echo product description in magento if the products belongs to specific category
body: <p>I want to show a detailed product description after a short description on the product listing page.</p>
  
  <p>I'm doing this:</p>
  
  <pre><code>&lt;?php $_product = Mage::getModel('catalog/product')-&gt;load($productId); ?&gt;
                  &lt;?php if(in_array(428, $_product-&gt;getCategoryIds())): ?&gt;
                      &lt;span&gt;&lt;?php echo $_product-&gt;getDescription(); ?&gt;&lt;/span&gt;
  
                  &lt;?php endif ?&gt;
  </code></pre>
  
  <p>It doesn't echo the product description though, any ideas what's wrong?</p>