This is the code I am using for the follow for Facebook, Twitter and Google.
The Facebook and Google work perfectly but the twitter button just points at the current page. My twitter url is http://twitter.com/tropicalvapors. Any help would be greatly appreciated. Thanks
<!-- AddThis Follow BEGIN -->
<p>Follow Us</p>
<div class="addthis_toolbox addthis_32x32_style addthis_vertical_style">
<a class="addthis_button_facebook_follow" addthis:userid="tropicalvapors"></a>
<a class="addthis_button_twitter_follow" addthis:userid="tropicalvapors"></a>
<a class="addthis_button_google_follow" addthis:userid="100440959384087032113"></a>
</div>
<script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js#pubid=ra-4fb3b1482c92f915"></script>
<!-- AddThis Follow END -->
That code seems to work for me. Can you post the link where you have the code not working? It might be an issue with some other JavaScript on your page.