problem with import of blender object

Hello everybody
I’ve got some troubles with my blender object in unity.
I try to apply material to this object but it doesn’t work.
I tried something very simple to understand what’s going on.

I create a cube in blender (normals direction outside) and export it in fbx.
In unity, I import the cube and put it on the scene.
I add a gameobject cube 100% unity.
I apply a material (shader: diffuse) to the 2 cubes.
No problem with the unity cube but nothing happens to the blender cube!!!
thanks in advance for your help.
croucrou (from Paris - sorry for my english)

Do you attach the material to the component that has the mesh renderer? Blender objects comes in as a hierarchical object.