...Or turn the light on...
Your question is a bit vague, I guess you mean that using the same lighting as your external view, you get blackness in your interior scene...? Remember, Maxwell is like using a camera... You'll need lower shutter speeds, maybe higher iso's & more light to illuminate an interior scene than an exterior. Just like in real life. Also, you might want to check that your glass is transparent enough to let light in... An example pic would better help us to help you...