南辕北辙
[词典] go south by driving the chariot north -- act in a way that defeats one's purpose; be poles apart; go south by driving the chariot northward -- act in direct contravention to; have nothing in common; poles apart;
[例句]后来，人们就把这个故事概括为“南辕北辙”，比喻一个人的行动和他的目的正好相反。
The idiom derived from this story indicates that one's action was the opposite effect to one's intention.