Hi Dani,
It seems then that it's the
<script src="http://static.ak.fbcdn.net/connect.php/js/FB.Share" type="text/javascript"></script>
part of the FB share code that is causing the selected page not to be used.
If you remove that, the FB share works, other than to fail to open the share confirm page in a pop-up window.
Presumably with an on-click new window, this would function as it should?