Material assigns to a wrong object I decided to practice normal mapping and followed through some tutorials. But something went wrong...

So, I have a scene with 3 cubes on 3 different layers. The one on the first layer is high-poly, second is low poly and third layer contains the cage. The low-poly one is unwrapped. I already baked the normal map, time to apply it to the object. And here's the problem:

I select the low-poly cube which I want to assign texture to, go to the texture tab and import the image... And for some reason the selected cube is black, but the one on the first layer has the material I just created! How is that possible? Why is texture assigned to the wrong object? No metter what I do, the cube that I need to apply the texture to stays black.

EDIT - SOLVED

I moved the cube from the second layer to the first one and now the material assigns correctly. So, for some reason the materials I create apply only to the first layer. Well, I think the problem is solved and I probably should read some more tutorials regarding layers. 

EDIT2

The reason why the cube on layer 2 showed in black - there's no lighting source on that layer! Yes, that simple

My .blend file can be found here:
As @batFINGER mentioned in his comment - the cube on layer 2 is black because there's no light source on that layer. Solved.