Manfred,
Thanks for all your patience and access to your site. We found the reason why the tags weren't working on your site. In the Social Configuration -> Misc tab of both JLinked and JFBConnect, there is a setting called "Admin Render Key". In JFBConnect, you had a value there. In JLinked, the value was blank. When both extensions are installed, the value for the Admin Render Key needs to be the same in both. That's an issue that we will be resolving in a future version (we'll likely make it so if both extensions are installed, you can only set the value in one and in the other, it will be greyed out).
When the Admin Render Key is set, let's say to "1234", you need to add the tags like:
{JFBCLogin key=1234}
The reason for the render key is so that on sites where user's can add their own content (like in Mosets Tree on your site), it prevents them from being able to add Like buttons, comment boxes and other social features to their own listings. That way, only you (the admin) can add that content.
I went ahead and set the Admin Render Key to the same value in both extensions. Then, I added the JFBCLogin tag to your "Disclaimer" article. You'll see if you go to that link that the Login Button is there. If you look at the actual Joomla article, you'll see exactly how I added it as well.
Hope that helps explain and gets you going with more of the social functions. Feel free to disable my account for now until more issues arise as well.
Please let us know if you need anything else, and good luck!
Alex