I have set up 3 spot lamps and a sun lamp to illuminate an interior. I have never used Cycles lighting before and I'm new to Cycles in general. I have played with the strength, size, and rotation of all the lamps but the lighting is always the same. It is highly diffuse, no shadows. The only thing that changes the lighting is the Ambient Occlusion fields in the World section of the Properties editor. If I uncheck that, everything goes black.
I am looking to give the setting natural indoor lighting, but the sky is black because it is the Moon, so World > Surface > Color is set to black. The sun filters down between very tall beams and through glass. It should cast the shadows of the beams, it is lined up to do so, but no shadows. The three spot lamps are intended to show the light filtering in from light tubes, but there is no sign of the lamps.
I imagine there is some basic thing I have done wrong. How do I correct this?
Edit: Objects with Emission shaders do work as lamps (I just tried it). So I could simply switch the lamps over to that, although that isn't going to help for the sun. I had understood that now most lamps work in Cycles, except for the Hemi lamp.