page tabs empty content

Hi Guys,
I've installed a clean verison, and it's working fine with the application displaying through facebook.

My issue is that the tab page is displaying a blank page. As far as I gather this is different from the "theme for tab not working" issue: http://drupal.org/node/1298606

Going to my tab setting in my site:
SHOWFACEBOOK PROFILE TABS
setting "View path" and "View path when page is liked" to "node/4"
l notice that when synchronizing the actual url that is being syncronized is:
[secure_page_tab_url] => https://<my_site>/fb_cb/190483771042181/fb_tab/view/
When I try to go to that url, I get an emply page (absolutly empty), and no errors are produced anywhere.
Question 1: is the above url being set correctly? (https://<my_site>/fb_cb/190483771042181/fb_tab/view/), and if so, why is this url displaying a blank page?

Actually, I've managed to display the tab, going directly to the facebook application management and changing the secure tab url manually to https://<my_site>/fb_cb/190483771042181/node/4
I then noticed that the theme is being displayed according to the configuration "Theme for profile tabs".

Question 2: is it a synchroniztion problem?

Thank you for you help!