I've probably missed something, but with C5 when I start with a new empty doc and then place an object in the scene and then afterwards decide to put a sky behind it by selecting a sky from the browser pane, the program adds a second camera1 and a greyed-out light and when I try to render there is nothing but blackness behind the object I originally created. So what am I doing wrong? Do I always have to start with a sky first?