--- D:/_Webs/www.prevencionintegral.com/public/sites/all/modules/ubercart/uc_attribute/uc_attribute.admin - Copy.inc	Wed Jul 17 12:39:52 2013
+++ D:/_Webs/www.prevencionintegral.com/public/sites/all/modules/ubercart/uc_attribute/uc_attribute.admin.inc	Wed Jul 17 18:44:36 2013
@@ -900,11 +900,11 @@
           'cost',
           'price',
           'weight',
           'ordering',
         ))
-        ->addExpression('po.ordering IS NULL', 'null_order');
+        ->addExpression('CASE WHEN po.ordering IS NULL THEN NULL ELSE 1 END', 'null_order');
 
       $query->condition('aid', $attribute->aid)
         ->orderBy('null_order')
         ->orderBy('po.ordering')
         ->orderBy('default_ordering')