Newbie: switching cameras


I just want to switch 2 cameras with the tab key, but i can’t.
If somebody have a blend file to teach me, i’ll be happy.

I use a property (prop=0)
When I press the TAB key, the camera is active (and the property must
change to “1” but i’m not sure).
When i press again the TAB key the other camera must be active
(because the property is equal to 1)… but it don’t work…

Take a look at

Hope it helps!