rendering and shadows

[simonrgeorge]

I have made a 3d-model of a house with materials and the sunlight. The sun hits the interior walls through the windows and lights these up nicely. Other walls that wouldn't get any sunlight don't light up. So far so good. The problem lies in the walls that don't get any sunlight. In the interior I am looking at two perpendicular walls. Looking through an opening in the wall of the closest wall to the perpendicular one that lies beyond the walls seem to fade into each other. After rendering the walls have the same shade. In my opinion the far away wall should be darker because it is further away from the facade. My computer seems to have another opinion. Can anyone help me persuade my computer that I am right!!
Thanks in advance
Simon George
(Amsterdam, the Netherlands)