Little help here?

[Nevadaref]

I disagree with the first two responders. I think that it is your responsibility to know that the ball went through the basket. It's not your primary responsibility, but you have to have enough awareness of this in order to properly administer the game.
Perhaps you are so focused on your area of coverage that you are failing to glance around the court at your partners and pick up where the ball is located every few seconds. You MUST do this. If you don't how will you know when to rotate?
Being aware that the ball went in is just about the same thing. You have to have an idea of what is happening in other areas of the court even though you are taking care of your primary.