Softkeys on Compaq 2510p

[Tester32]

Dear specialists,

I have the Linux Mint 14 XFCE, 32-bit installed on a Compag 2510p from HP. The keyboard layout is German or Russian (I switch these languages).

The softkeys like
* Fn+F3 for sleeping,
* Fn+F9/F10 for brightness
* Fn+F11 for contrast
are not working. Nothing happens if I press on that keys.

On another partition i have installed an Ubuntu 12.10 LTS 32-bit with Unity and it works.

How can I add the softkeys in Mint 14, please? They are very usefull, using them saves battery power.

Additional information:
CPU~Dual core Intel Core2 Duo CPU U7600 (-MCP-) clocked at Min:800.000Mhz Max:1200.000Mhz Kernel~3.5.0-17-generic i686 Up~22 min Mem~416.6/1992.9MB HDD~80.0GB(37.7% used) Procs~154 Client~Shell inxi~1.8.4

Thanks in advice for your answers.