Nvidia gts 250 dual screen (second dvi)

[sasta]

I have tried everything I found (gfx string: ok but no second screen, nvinject:nothing more) but I can't make my second dvi work. When I plug the second dvi the main screen goes black or it hangs. When I boot with two screens attached I can't get to gui, only one black screen and the other not working at all (no signal).
Any help would be appreciated.
Thanks