Gnome Shell Integration Firefox plugin not working

I installed ubuntu 11.10 a few days ago, and I didn't liked Unity so I 
installed Gnome 3. Then I discovered extensions, I installed a few 
manually until I right clicked the Firefox icon on the dash and I saw 
some option to install a plugin for gnome extensions website 
integration, I did it. Now I can see the plugin installed and enabled on 
Firefox.

So I went to extensions.gnome.org and started clicking the "On/Off" 
button to install the extensions I wanted (I didn't got any message or 
notification), I rebooted, and non of the extensions were installed. (I 
use gnome-tweak-tool to enable them and also searched on the extensions 
folders on both /.local/ and /usr/share/ and no new files were created)

I then checked firefox error console while clicking the on/off buttons 
but didn't saw anything.

If I go to the "installed extensions" section of the website I can see 
the list of the extensions I installed manually, and if I click the 
"On/Off" button the extension gets enabled/disabled on the fly.

What can I do to find why this is not working and fix it?

OS: Ubuntu 11.10 x86
Kernel: 3.0.0-14-generic
Gnome: version 3.2.1
Gnome Shell Integration plugin: Last Updated 12/20/2011
Firefox: version 9.0.1