The primary job of the filmmaker is to control the experience the audience has when they view the film. You wan them to share the emotions you are intending, engage the story as if it was really happening, and decide for themselves at certain times. To do this you have to establish a number of things early on in the story. This means understanding whom the characters are, what motivates them, and what the status of the relationships between them are. For example, if two people have a very intimate friendship, but this is mis-communicated to the audience as a romantic or sexual relationship then they are immediately off base and the rest of the film will not work.