gnome-control-center cannot change keyboard shortcuts in gnome shell

[Vincent Povirk]

I'm using Ubuntu 12.04 64-bit, with the Gnome desktop environment.

Gnome-control-center is version 1:3.4.2-0ubuntu0.2.

Steps to reproduce:
1. Click on the username at the upper-right corner of the screen in gnome shell.
2. Click on "System Settings".
3. Click on "Keyboard" and go to the "Shortcuts" tab.
4. Click on "Navigation" and scroll to the "Move to workspace below" item".
5. Click on the right column and enter a new shortcut key for "Move to workspace below".
6. Press the shortcut key.

Expected result:
The workspace switches to the one below.

Actual result:
Nothing happens.