Lighting problem

Okay this may sound weird at first but.... I have this model, and a couple lights, right? So I have all the lights turned OFF, and I have only Ambient Occlusion turned on in the effects tab, so it looks really nice. but here's the problem. I have this motion tracked footage of my backyard, so for my model, I have a blue screen set up under it so I can key it out later and so it makes a shadow, right? But as you all know, when you first start a project in cinema 4d, there are no lights, and you make a cube object, if you move the camera, it like changes the way the cube is shaded, (or something the colors just change when you move the camera if there are no lights) So basically, that's whats happening to my blue floor, which would make it useless. But I can turn on the light, or it will mess up the color of the model (its a reflective surface) so, any way to turn that auto shading? like the blue screen will go from blue to black and to blue again, really frustrating. please help.

yes but you see the whole reason for the blue screen would be for the model to cast a shadow so it looks like it was actually standing in the shot, but thanks anyways, the shot was at a angle so I was able to tilt the blue screen and it doesn't dim and I still have a shadow.