I have installed Gnome 3 on Ubuntu today following this [guide](http://www.filiwiese.com/installing-gnome-on-ubuntu-12-04-precise-pangolin/). All worked well and I have installed the extensions mentioned without problem.

However, after logging out and in, all extensions were gone. Going to the Gnome extensions website, I saw that all my extensions were outdated and that I could install only one other extension.

I'm rather new to Ubuntu and completely new to Gnome. I don't even know how to check my own version (there's no mention of Gnome in System Information) - I reasoned maybe I'm using an outdated version, even though `apt-get` update/upgrade/dist-upgrade does not upgrade anything or solves the problem.

How do I get things back working? I've uninstalled all my extensions, but that didn't do the trick, either.

Update: I tried to install the one extension the gnome website shows as valid, but nothing happens; same when trying to install 'outdated' extensions. I see the popup, choose install, nothing happens.