I'm having the same problem too.
I have gnome 3.6 on Ubuntu 12.10 and have enabled Alternative Status Menu from Tweak Tools > Shell Extensions. Still, when I want to Suspend the system for a while, I click on the Suspend button from the Username menu in the top right corner of Gnome desktop environment but nothing happens. In Unity desktop environment, everything works fine.
I'm having the same problem too.
I have gnome 3.6 on Ubuntu 12.10 and have enabled Alternative Status Menu from Tweak Tools > Shell Extensions. Still, when I want to Suspend the system for a while, I click on the Suspend button from the Username menu in the top right corner of Gnome desktop environment but nothing happens. In Unity desktop environment, everything works fine.