Because the screen is not square to the camera, simply. A screen reflects most light directly at 180 degrees from the light source, so you need the camera in line with the projector, and Bob's yer Uncle. Try it!
Have the screen at an angle means all you see is white, as you saw.
On Nov 15, 2013, at 5:21 AM, David Lewis wrote:
> I wonder why the camera cannot see the projections; is it due
> to the glare from interior lighting