Lion: four finger swipe to switch desktops (spaces) works on internal trackpad but not magic trackpad? Even though in the pref pane for Trackpad it says "Swipe between full-screen apps" when I'm using the internal trackpad in my laptop, it will switch desktops even if I'm not using full screen apps. However, when I'm using my Magic Trackpad, the 4-finger swipe does not switch desktops.

Anyone have a solution?
Do any 4 finger gestures work? If not, it's likely the trackpad faulty and not just some software bug in Mission Control.