Why you can't see anything:
The reason (or at least one of) is due to a limitation of normal mapping. All that normal mapping can do is trick cycles into think the face is at a different angle. In your case, if you look at what you're trying to create from the top, all the faces are the same angle. In order for this to work, you need a bit of a slope.
Using displacement would work well, except in order to have enough geometry to displace, you will mess up the wire frame :/
The reason why the normal map node works, is that it supports some very unconventional normal maps. The bump map node is more particular about its output.
As far as Ray Mairlot's comment, a brick texture won't work form the bump map node either, I have tested it to check, there is only a slight edge visible along the slope that occurs between the bricks.
The bump and normal nodes are different:
The Normal Map node takes a color representation of a normal vector and turns it into a vector.
The bump nodes samples 2 areas on the height map and compares the angle the find the vector. since there is only black and white, it will only find 90 degree angles and therefore not show any edge.
Paraphrased From the wiki