meerweten:
after a long search i finely found a working solution:
i rolled back the ftdi driver to the previuos version (standard versionh for windows 8) the .28 and not the .30
so it seems that my nano contains a ft232 replica,
but wxhat i don't get is why i couldn't load a sketch wit another ft232 breakout (homemade) that works fine with my pro mini?