Imported models an physics

I tried to add in the scene an imported model (3ds) with any nodes.

Once added the player falls down in the space.

For each node of model the system told me, for example :

WARNING: no model bound: NoName+Leg_plate (com.jme.scene.TriMesh)

in fact the model has no boundings, and than I think the physics system cannot handle this.

Now, when I try to do :

   model.setModelBound(new BoundingBox());  

The app crashes telling :

WARNING: Skipped geometry:
java.lang.IllegalArgumentException: Extent cannot have a component that is 0 to generate collision geometries!
   at com.jmex.physics.PhysicsNode.createPhysicsGeometry(
   at com.jmex.physics.PhysicsNode.addPhysicsGeometries(
   at com.jmex.physics.PhysicsNode.addPhysicsGeometries(
   at com.jmex.physics.PhysicsNode.generatePhysicsGeometry(
   at com.jmex.physics.PhysicsNode.generatePhysicsGeometry(
   at it.local.physic.TestPhysics.initGame(
   at Source)
   at it.local.physic.TestPhysics.main(

Well, I think the problem is reguarding the model, each node shuld have the appropriate bound, isn't it ?
I found no example and no guide, a link will be appreciated.

It's hard to be a newbee but someone must be.

Boundings are already needed for correct rendering of the scene. The last error message means that you either have a geometry with a scale containing a component that is 0, or your model bound has 0 with, height or depth. This can happen when you have a sub-mesh, which has all its triangle in the same plane. To avoid the error you can either create your physics collision geometry manually, you can search for the bound and enlarge it a bit, or you can change your model accordingly.