markup is removed in text block

Hi. I’ve been trying to add a block of code in the Text Block (within Text, not Visual) but the content gets removed automatically.

Here’s what I’m trying to add (in case this is the issue):

<!– AddThis Button BEGIN –>
<div class=”addthis_toolbox addthis_default_style “>


</div>
<script type=”text/javascript” src=”http://s7.addthis.com/js/250/addthis_widget.js#pubid=xa-4f2f173a5004e335″></script&gt;
<!– AddThis Button END –>

I’ve tried adding the tag around it, but that didn't work either.

Thank you in advance.