My shadows are not working... Please help!

So I just started and have watched a couple of tutorials about lighting. I added the directional light and positioned it toward a mannequin (default mannequin) and it wont show a shadow. I checked the settings for the light, and it was perfect. I even added an atmospheric fog, and a skylight, and it still did not work. I looked it up and i still could not find the answer. Thanks!