Problem with shadows or model?

I have the following problem with one of my models. I’ve created the chest with Blender, although it seems all the edges of the chest are there, you can see the light passing through them.

50030-shadows-problem.png

Any idea what it can be?

Thank you very much!

EDIT: Model added.
https://drive.google.com/file/d/0B3ELWKyJ3vaOLUkyU0EzcXJ4YU0/view?usp=sharing

EDIT2: Added .fbx file
https://drive.google.com/file/d/0B3ELWKyJ3vaObktzRUFMZEo0V2c/view?usp=sharing

I found the problem.

In the (Skinned Mesh Renderer) component I had the option “Cast Shadows” set to “On”. If I set that option to “Two Sided” the problem is solved.