I may be wrong here, but, shouldnt (approx) line 308 in class.AWD_facebook_likebox.php start with :
<fb:like-box ... instead of <fb:likebox ...
and end in
</fb:like-box> instead of </fb:activity> ?
basically - in my case anyway - the xfbml version of the likebox does not work until i change those lines. could of course all be my fault . just checking .