Shadows penetrate through objects?

Hi. When a directional light is used with shadows enabled(in realtime), the shadows are rendered just fine, the way they should. However, when the scene is baked, there is a problem. I have a structure over which there is a box which can be moved around.This box obviously is not marked static and isn't baked. The structure though is baked.However, when the box is brought near the edge of the structure, the shadow is cast on the walls of the structure AND on the ground below the structure as if the shadow penetrates through the structure and falls on the ground. This doesn't happen in real world so definitely, this shouldn't happen in the game either. Any help or guidance is appreciated. Thanks.