Note "but nothing"... is not very informative.
What exactly happens? BS.Player's control panel is on your PC's screen?
What's more important. You fail to provide some relevant data.
Geforce/Nvidia or ATI card?
Using (nView) Clone mode or DualView or Ati's theater mode or ...?
What is selected as "Rendering mode" under
(rightclick >) Options > Preferences > Video > [Video rendering]?