barking up the wrong tree
(Informal)
Looking for something in the wrong place or doing the wrong thing
Context:-Mandy told me she's now interested in journalism. She keeps changing her mind!
-Yes, I know! She really can't stick to one idea. I personally think she should have stayed in that lab and kept on nurturing her scientific side.
-Ever since she left the lab she's been barking up the wrong tree. Journalism for one, really isn't her thing.
-Try telling her that!
Notes: a metaphorical meaning - when a dog barks up a tree where it thinks an animal is taking refuge in order to run away from it.
Category: b, informal, animals,plants,nature