Because of Unity's inability to use any Gnome panel applets, I changed back to the classic gnome panel.
However, even in the classic interface, I'm finding I can't right-click the Gnome panel to change anything.
How do you add applets to the Gnome panel in the classic interface?
Hold Alt and Right Click. I had the exact same problem actually, but more with the clock in the middle of the screen driving me batty. :)
See: How do I move the clock in GNOME Classic?
If you are using gnome-classic (with effects), you actually have to hold Meta + Alt + Right Click.