Shininess disappears when using NormalMap (Materials Tutorial)

I am currently going through the beginner tutorials, and have just finished the materials example (

Everything in the example runs fine except for the shininess on the rock sphere. It works fine if I uncomment the following line:

[java]mat_lit.setTexture(“NormalMap”, assetManager.loadTexture(“Textures/Terrain/Pond/Pond_normal.png”));[/java]

Obviously the sphere loses its ‘3D’ texture appearance, but the shininess works. If I leave the line in as per the tutorial code, the rock sphere appears as it should except for shininess.

Does anyone have any ideas why this is happening?