Default Only USB or Serial on display

hey guys,
i think that other threads have the same problem, but i tried all methods, but nothing helps.

The computer always show that no connection is between the mda compact 2 and the computer. the pda only display Serial or, if the usb cable is pluged in, USB.

But why does the computer does not realize the mda?
I tried it from windows xp and from windows 7. nothing.

Maybe i have the wrong drivers?

king regards,

niiine