I need help understanding why shaders when applied to a block (e.g. cube) some of it's sides are black, and some side look different from each other although the same shader is applied.

Also sometimes the shader is applied to the back side of the block although no light sources is near to it. I will provide the sample test project to see exactly what I mean

Here is the link to the test project
http://www.box.net/shared/zg4gtgq7d6