How to select custom sessions from GDM

["Robert Gibbs" <gibbsrc gmail com>]

In the Gnome Desktop User's Guide under "Session Preferences -> Setting Session Preferences", there is a detailed explanation on how to create custom sessions.

At the bottom it says, "When you log in on GDM, you choose
a session. When you choose a session, you can select which of the multiple
sessions to use."

I would like to do this.  I open a bunch of applications then I open gnome-session-properties.  I press "Add" and give my session the name "Stuff".  I select "Automatically save changes to session", then logout.

At the GDM login display, I am expecting to see a session choice of "Stuff", but I do not.  In fact I have found no way to make any of my custom sessions show up at GDM. 

Is this a broken feature or am I doing something wrong? Can anyone tell me how to get these custom session to appear on the GDM login?

Thanks
Bob Gibbs