Suspend and Hibernate do not exist

When I type "suspend" or "hibernate" I receive "No results found".
I expect to see an option "Suspend" or "Hibernate", which would suspend or hibernate my computer.

I can suspend and hibernate from my system menu, although sometimes the computer does not wake up.
I might have problems with my power setup, but I would expect synapse to show the option nevertheless,
as the system menu does show it.

"Log out", "Shut down", and "Restart", however, work from synapse perfectly.

I've run a few commands in my terminal to help debug:

upower -v
UPower client version 0.9.15
UPower daemon version 0.9.15

dbus-send --system --dest=org.freedesktop.UPower --print-reply /org/freedesktop/UPower org.freedesktop.UPower.HibernateAllowed
method return sender=:1.24 -> dest=:1.80 reply_serial=2
   boolean false

SYNAPSE_DEBUG=1 synapse output shows nothing useful, two irrelevant warnings, and a lot of completely normal debug output.
[20:31:58.721949 Gtk-Warning] Unable to locate theme engine in module_path: "pixmap",
[20:31:58.722104 Gtk-Warning] Unable to locate theme engine in module_path: "pixmap",
[20:31:58.722224 Gtk-Warning] Unable to locate theme engine in module_path: "pixmap",
[20:31:58.723585 Gtk-Warning] Unable to locate theme engine in module_path: "pixmap",
[20:31:58.874061 Info] [GnomeSessionPlugin] org.gnome.SessionManager is available
[20:31:58.875168 Warning] [SshPlugin] /home/denis/.ssh/config: Error opening file: No such file or directory

I run Ubuntu 12.04 with Gnome 3 session with gnome-panel.