The environment cannot be sampled that way as it would be too costly performance-wise (you would have to render the scene multiple times, each time with a different camera location).
The most common workaround for env sampling is called "environment maps" or "reflection maps". For this you usually have to place "taps" to locations where you want to sample the environment and capture it to a cube texture, then use that texture from the material ... however I'm not sure if this is supported in D:OS. At least I haven't found any sign of environment map generation support.
