I was working with a light in one comp and I was able to the shadow cast on the layer I want it being cast on. Then I moved the casting layer slightly above so it would not be cut by the receiving layer and the shadow is gone.
I deleted the light and created a new one, made sure that cast shadows is enabled for both the light and the casting object, and accepts shadows is also enabled for the receiving layer. I looked at separate views and both the casting and receiving layers are close together as well as the light, which has the falloff set to none. The shadow still refuses to show.