I'm trying to put a bookmarking and sharing tool into a website but can't figure out how to do it. I have some code, and it displays icons and the links on the icons are live. but when I try to click on the links to take me through to the sites, they don't work.
Any idea why?
Here's the code i have.

<div class="addthis_toolbox addthis_default_style">
<a class="addthis_button_facebook"><a href="http://www.facebook.com"></a></a>
<a class="addthis_button_myspace"></a>
<a class="addthis_button_bebo"></a>
<a class="addthis_button_digg"></a>
<a class="addthis_button_delicious"></a>
</div>
<script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js?pub=xa-4a5c63f75dbb8e04"></script>