Normals not scaling / Inverting?


I am loading a .obj file into my scene, and lighting it with a PointLight. Everything works fine, but when I scale the object up by more than around 5 times, I find that the light is affecting the inside of the object, instead of the outside, as if the normals are being inverted. The light still affects some parts of the object, but most of it appears flat grey, (ie the base emissive level of the object). It's almost as if the normals are being "left behind" as the object scales.

The object is being exported from Blender 2.5-Alpha2. It is definately not a case of needing to flip my normals, as it works fine at normal scale.

Here's my object loading code, copied straight out of a page of this forum:

       ObjToJme converter = new ObjToJme();
       File file = new File("Data/models/world1.obj");
       URL objFile = null;
       objFile = file.toURL();
       converter.setProperty("mtllib", objFile);
       ByteArrayOutputStream BO = new ByteArrayOutputStream();
       System.out.println("Starting to convert .obj to .jme");
       converter.convert(objFile.openStream(), BO);
       TriMesh model = (TriMesh) BinaryImporter.getInstance().load(new ByteArrayInputStream(BO.toByteArray()));
       model.setModelBound(new BoundingSphere());
       setEmissive(model, 0.2f); //just a convenience function
            model.setLocalScale(10); //this is where it all goes wrong.

Am I just doing something n00b1sh? Thanks.

maybe the pointlight is inside the model ?