We purchased a rigged human anatomy model. It has several layers, materials and textures and appears to be very complex. The scene came set up. I can see everything in rendered shading however when I actually go to render it out, the output is completely black. I'm using cycles, composite node is connected correctly, I have a camera and 2 lights. I've searched all over the web and have tried everything that is suggested and nothing seems to solve this problem. Is this a settings issue or could this be a graphics card issue? I'm working on an iMac 3.4 GHz Intel Core i7, 32GB memory with an NVIDIA GeForce GTX 680MX 2048MB graphics card. I am completely lost so any advise would be greatly appreciated.