I just investigated further as to what's happening.
When JFBConnect tries to autopost content, we make a call to the front-end of the site to get the SEF version of the URL to be posted. However, that call is failing when being made from the admin area of your site.
When that call is made, it makes a request like:
index.php?option=com_jfbconnect&task=ajax.sef&url=aW5kZXgucGhwP29wdGlvbj1jb21fZWFzeWJsb2cmdmlldz1lbnRyeSZpZD05ODU=
If I go to that URL directly, it works. From the admin area making the call, it fails with the following error:
Forbidden
You don't have permission to access /dev/index.php on this server.
Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.
I'm not sure what's causing that as it seems like it may be a firewall or other server configuration issue not allowing the admin area to call the front-end of your site. Because that call is failing, the URL was just being the relative link.
I've made a change on your site which should generate a working URL including the domain. Please test and let me know if that works for you.
Thanks,
Alex