IDL adds the light that bounces off from props, figures and the background. You still need a "proper" light source: Either one of the conventional lights or a simple prop with a strong ambient value. I suggest you start by adding one of BagginsBill's environment spheres to an empty scene, add a figure, enable IDL, add a single infinite light and see what happens. You also need Gamma Correction enabled and set to 2.2 for IDL to work properly. Your figure skin shaders need correct Gamma Correction, too, so download SnarlyGribblys SceneFixer and EZSkin scripts.