Either that, or it's a black lining or something.
Besides - not even <b>night vision</b> can work in <b>absolute dark</b>. Remember - what you're seeing, and what anything is seeing, is light reflecting off a surface. If there is no light, then there can be no vision, period. Night vision works by magnifying what light is available (I'm not an expert on night vision, so if this isn't exactly correct, don't bother flaming). So there's got to be <b>some</b> light for that to even work. So it could be a shadow, and that would be why.
