How did that not go in? Crazy scenes in the FA Cup

Despite having progressed to the next round of the FA Cup, WBA were on the wrong end of an extraordinary incident during their FA Cup tie at the Valley. 

Charlie Austin, in one of their attacks, got on the end of a post shot by a teammate to score. But he was somehow denied by the bounce of the ball. 

After shooting with his right foot, the goalie got a hand to the ball and it was going into the net. However, the spin of the ball left everyone gobsmacked. The ball spun away from goal and Charlton miraculously survived.