I cannot connect my MacBook Air to an external monitor. But I am able to connect it to a projector, without any difficulty. My computer detects the external monitor but cannot connect to it. The screen is just black
- I have tried everything in the System Preferences > Display > Resolution category. Does not work, but any clue will help!
- I have upgraded everything on my Mac, so that it is now OS X El Capitan.
- I have tried to deconnect and reconnent the cable connecting to the screen.
- Other MacBook Air work with the monitors I want to use, and they all work.
- I have tried the sleep-mode to get it to detect the mac/screen.
- I have tried changing the VGA cable.
I have tried almost everything, what am I missing?