Now I tried to installed "User Albums" and "Blog" add-ons. I am seeing no changes at all. I adjusted the setting via admin, and made sure that the admin has all permissions set to "allow". However, I am see no changes to the site at all. No even the Default Style...
Any idea what causes this? I manged to get a few add-ons installed, like xenPorta and the last one I installed was "ToggleMe". Those add-ons work fine.