It's strange, in the HTML on your page is the following code:
<div style="position: relative; top:0px; left:0px; z-index: 99;" class="jfbcfan">
</div>So, our module is working and adds the proper div, but the inside text of the div (which should be showing the Fan module) is missing completely. The only time we've seen that before is when there's an optimization plugin that's stripping that code for some reason. I went through the code in the Active Groups module you mentioned, and there's no reason it should be doing that.
Can you try the following and test after each:
* Disable any Caching or optimization plugins/extensions you may have enabled on your site.
* Re-order the JFBCSystem plugin so it's the lowest number/first plugin to execute.
* Re-order the JFBCSystem plugin so it's the highest number/last plugin to execute.
Hopefully, one of those will make things work. If so, that will help narrow things down, and if it causes other issues, we'll be able to help fix those.
Thanks,
Alex