AddThis

Don't see any icons except in ie9. Nothing in Firefox or Chrome

I am working on a site and I have everything working if you use IE browers but not if you use Firefox or Chrome. The icons disappear. How can I fix this.

Here is my code:
<!-- AddThis Button BEGIN -->
<div class="addthis_toolbox addthis_default_style ">
<font face="Trebuchet MS" size="2">Share:&nbsp;&nbsp;</font>
<a class="addthis_button_facebook"></a>
<a class="addthis_button_twitter"></a>
<a class="addthis_button_delicious"></a>
<a class="addthis_button_digg"></a>
<a class="addthis_button_stumbleupon"></a>
<a class="addthis_button_reddit"></a>
<a class="addthis_button_linkedin"></a>
<a class="addthis_button_google_plusone"></a>
<a class="addthis_button_compact"></a>
</div>
<script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js#pubid=ra-4e7769002fcd4494"></script>
<!-- AddThis Button END -->

Here is my webpage: www.newlookinstitute.com
Any advise is appreciated.