Adding material to boxes work, but not to a plane (used as wall) imported from Blender

Hi friends,

True n00b here, so go easy on me. I read the FAQ regarding materials, but nothing in it stood out as the cause for me (been known to be mistaken from time to time though...).
I created a level in Blender (the version that was newest 4-5 months ago), and imported it into Unity (the one that was new at that time, but I have today updated to 4.5.3, and I see the same thing). And I seem to have some issue getting textures on it.
I also created a sphere and a ball in Unity, and those objects accept my materials just fine.
I tried to change the shade on the material, but the grey color just changes a bit. Still no real image so to speak.

What would you guess I made as a true n00b error?

In case someone thinks it is easier to just try my small level instead of guessing which error I made, I uploaded the project to Dropbox https://www.dropbox.com/s/m1fk4qtnj2z2l65/FPS-test1 3b Sep2014.zip?dl=0

It is the walls and the floor I can't et any material on.

 

There are two possibilities... the first is that your normal are incorrect... but then you wouldn't see anything at all. The most likely culprit is that you don't have UV Mapping on those planes. You need to make sure they are UV mapped so you can texture them in Unity.

 

Thank you Dustin! That was exactly it