[TYPO3-shop] ###FIELD_QTY### always empty when showing variants

[Juan Pablo Villaverde]

I have an ITEM_LIST_RELATED_TEMPLATE showing the ###PRODUCT_TITLE### and the 
###FIELD_QTY###, my template works ok EXCEPT when I show a variant field, 
like ###PRODUCT_COLOR###. If I show a variant field, the FIELD_QTY field is 
always empty. Seem like a bug in the extension.. or maybe i am not 
considering something.
Any help will be very appreciated.

My template:

<!-- ###ITEM_LIST_RELATED_TEMPLATE### begin
 This subpart is used to display the regular list of products. It's also 
used by search-results.
-->
 <!-- ###ITEM_CATEGORY_AND_ITEMS### begin -->
 <!-- ###ITEM_LIST### begin -->
        <!-- ###ITEM_SINGLE### begin-->
   <tr>
  <td>###PRODUCT_TITLE###</td>
  <td>###PRODUCT_COLOR###</td>
  <td><input type="text" name="###FIELD_NAME###" value="###FIELD_QTY###" 
class="unidades" /></td>
   </tr>
          <!-- ###ITEM_SINGLE### end -->
  <!-- ###ITEM_LIST### end -->
 <!-- ###ITEM_CATEGORY_AND_ITEMS### end -->
<!-- ###ITEM_LIST_RELATED_TEMPLATE### end -->