Unless it is in the judgment that each parent is responsible for ensuring attendance at extra-curricular activities during his or her parenting time, the father is not responsible for that activity during his parenting time. Unfortunately for your son, the law does not allow children, no matter what age, to veto parenting time. Consider asking his father if he would exercise his parenting time by attending the event. Discuss the importance of this activity to his son. See if he would be willing to change his parenting time night to another evening. The courts encourage parents to facilitate these activities by communicating with one another on behalf of the child. Remember, the court's first priority is always the child's best interest. Keep that in the forefront of all your communication with his father.