It is still wrong though; The shadow on the floor is at a 45 degree angle, which should make the eastern walls just as shaded as the northern walls.
Additionally, even though the wall blocks are top-lit (as can be seen from their shading) it seems like the topmost bricks in the wall are darker than the bottom ones.
And finally the wall lamps are a bit confusing to me, first because they sit on the darker topmost blocks and second because they only shed a tiny bit of light on the blocks themselves (since you can see that the shadow on the floor has nothing to do with the lamps). I'd say that since this is obviously an outside daytime scenario it makes little sense for lamps to be around and lit (you could turn them off which would suggest that they are there to supply light during the night, or you could change the whole lighting to indicate that this is a closed building or somesuch and thus it should have no global lighting (which is what makes the southern walls brighter and casts a 45 degree shadow everywhere)
Other than the lighting I actually like the art, it makes me want to make something similar (though I really don't have any spare time :S)