Hi! I am beginner with the Manual Mode of my Nikon D3100 and I noticed that as I was using the “Infant Indoor” Cheat Sheet I ran into a problem. When I took a picture without the flash the photo turned out completely black no matter where I shot the photo. But when I took the photo with the flash it turned out just fine. I don’t think it’s a mechanical issue but a setting that is set wrong. Any advice on how to fix this?? I’m sure it’s simple but I’m still learning. Please help! Thanks!