Set a specific url for featured thumbnail

Hi, I can’t set a specific url for featured thumbnail. When I add featured thumbnail, in the tab I set the url in “Link Url” field but the featured thumbnail always redirect to post.

I use Arthemia theme. The function is:

<?php if (has_post_thumbnail()) {
?>
<a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>">
<?php the_post_thumbnail('front-list',array('class'=>'front-list-thumb-wrapper', 'title'=>$title)); ?>
</a>
<?php
} else