Well, I can't get the applet to work on an html... only on the applet Viewer on NetBeans. Perhaps there's something wrong with the dir to the resources?
public static final String Texture_LightPlayerPiece = "/data/marble.jpg";
public static final String Texture_DarkPlayerPiece = "/data/wood.jpg";
texMan.addTexture("LightPlayerPiece", new Texture(documentBase, Resources.Texture_LightPlayerPiece));
texMan.addTexture("DarkPlayerPiece", new Texture(documentBase, Resources.Texture_DarkPlayerPiece));
What exception do you get?
Are u using a jar file? if using a jar file if so then the 3d files and textures have to be outside the jar file. Are you using software or hardware rendering???
Have you set the codebase-attribute in the applet tag? It could also be worth a try to put the resources into the same directory as the applet and then do a simple public static final String Texture_LightPlayerPiece = "marble.jpg";
public static final String Texture_DarkPlayerPiece = "wood.jpg";
Just to see, if the directory is causing the problem somehow.