"Barking up the wrong tree" - it means that you make a wrong choice by accusing or asking the wrong person or searching in the wrong place.(обвинявам несправедливо; говоря с неправилния човек; търся не там, където трябва)

Example: You are barking up the wrong tree this time, because I wasn't here last week so I have no idea who forgot to turn off the lights on Friday.