Making a mistake or a false assumption in something you are trying to achieve.
If you're barking up the wrong tree, you're looking for something in the wrong place or going about something in the wrong way.
it means she has placed the source of her dissatisfaction on the wrong person...a person that possessed no fault in the current grievance
The phrase means to discuss something completely different from the subject in hand or to be confused as to the expected response
If you are a dog, and you are chasing a squirrel or other tree-climbing animal, you follow them to the tree and bark at them. If you bark up the wrong tree, you are barking at nothing, so the idiom means you are on the wrong track; you are making a fuss at the wrong person or over the wrong thing.
You are barking up the wrong tree ... when you have come to the wrong conclusion. You need to look at the situation and look at other options...
You hear people say that someone involved in a misdirected enterprise is "barking up the wrong tree."
This surely arises from the days when it was common to hunt with a dog. The dog would "tree a squirrel" or raccoon or whatever and bark energetically looking up from the base of the tree. It is a common enough occurrence now that dogs chase squirrels or cats or whatever and then sit at the base of a tree barking. But, in a forest, the squirrel or raccoon can change trees and the dog will still focus on the tree where the dog thinks the squirrel was last seen and so remain, "barking up the wrong tree."
The idiom implies the person "barking up the wrong tree" is taking action in a direction that is completely wrong to achieve a goal. "If he thinks he is going to get the promotion by wearing a new suit, he is barking up the wrong tree."
Misguided assumption, on the wrong track, wrong course of action
