noun
barking up the wrong tree; calling at the wrong house
Used when someone's approach, target, or assumption is mistaken; often appears in the set phrase お門違い (o-kadochigai) with the honorific prefix.
See also: 御門違い
彼に文句を言うのはお門違いだよ。
Complaining to him is barking up the wrong tree.
その苦情はうちの部署ではなく、お門違いです。
That complaint is for the wrong department; you're calling at the wrong house.