FN+F8 does not change monitors

[p4trykx]

Hello
I've just upgraded from Ubuntu 11.04 and I have a problem with FN+F8 keys which should cycle through external display modes. In 11.04 when I push this combination i get, only laptop display->clone->tow screens etc.
On Mint 13 nothing happens. I have a Latitude E6500 laptop with Intel graphics card. As a substitute I use now a applet called Jupiter so but it would be easier If i could do with key combination.