Streaming fullscreen with Open Broadcaster Software gives black screen

After a long while i figured out how to stream in HD. However, every time I stream in fullscreen, the stream will show a black screen instead. If I stream a game in Windowed mode it will show it without any issues.

How can I stream a game in full screen mode so I can prevent them from seeing my desktop and give them the optimal quality resolution?

I'm using Open Broadcaster Software and have set my settings to entire screen.