Slapping the backboard

[crazy voyager]

This may be becuse FIBA's rules are diffrent...
31.2.4 Interference occurs during a shot for a field goal when:
• A player touches the basket or the backboard while the ball is in contact with the ring.
• A defensive player causes the backboard or the ring to vibrate in such a way that, in the judgement of the official, the ball has been prevented from entering the basket.
• An offensive player causes the backboard or the ring to vibrate in such a way that, in the judgement of the official, the ball has been caused to enter the basket.

In other words if you slap the BB in a fiba game, and you (in the officials judgment) prevent (defense) or cause (offense) the ball (not) to enter the basket, that is BI and points should be awarded or removed.
But listen to the other guys in your case I am just speculating in why people never learn the rule properly