Why the Bumped Diffuse shader doesn't work?

Hi, I make the mesh in Blender and I want to let it have sand effect by using Bumped Diffuse in Unity. But it works out in all the same color, why? ( Picture Here ) I learn Blender and Unity on the Internet, the learning video are all fine and never have problem like this, so I’m really really confused. In an other way I do the UV mapping picture replace the sand picture, but it still the same. What part of the step did I miss? Help me, thanks!

You need to set the sand texture on the Bumped/Diffuse shader, and a normal map on the Bumped Diffuse Shader.

You then need to make sure your model you imported from blender has this Bumped/Diffuse material assigned to it.