Over the last four years of writing on this blog I cannot tell you how many times I have gotten an email about this. I have no idea why it took me so long to publish it in a post...
Generically speaking, the email goes like this:
"I have an interior rendering with lights and when I render the view the room is black"
To which I reply:
"Are the lights on? Is the render set to use artificial lights? What light family are you using?" etc...
By the second or third email I will usually have them send me the Revit file, knowing full well what the problem is going to be. Your camera is in the wall! Say what?? ...
That's right... Your camera is inside a wall or some other model element.
Revit has this quirky little bug (even in the latest version, 2014) where you can place a camera that is technically inside of an element and still see the view.
Notice where the cameras are placed? If I try to render image A's view I get a black screen. If I render Image B's view I get a rendering. But the viewport displays a view! I have no idea why Revit shows an image when it's camera is inside of an object but it does.
In conclusion, next time your try to render a scene and it renders all black check your cameras location.