Microsoft Bluetooth mouse 5000 button 4

Dear all,

I have a Microsoft Bluetooth mouse 5000 and after upgrading to Mac OS X v10.7 Lion I can't get my button 4 to work. It's a button on the left hand side of the mouse and I use to have "Exposé - All Windows" assigned to it.

To do so, I have installed "Microsoft IntelliPoint" and it used to work as a charm with Snow Leopard. Now even if I assign "Click" to the 4th button it doesn't work, it's like the button is not there.

I would like to assign "Mission Control" now to that button, but I just can't get to work. Anyone with the same issue?

Please see bellow some screenshots.

Tks,