Barking up the wrong tree means blaming or pursuing entirely the wrong thing. You are barking up the wrong tree, quite barking up the wrong tree.
It says the effort is sincere and misdirected, which is gentler than saying somebody is wrong. The picture is from hunting dogs baying at a tree the animal has already left.
1phrasebarking up the wrong treeBlaming or pursuing entirely the wrong thing.
“If they suspect the night staff they are barking up the wrong tree.”
barking up the wrong tree is a phrase.
Also accepted in games: bark up the wrong tree
bark up the wrong tree An allusion to a situation in which a hunting dog misidentifies the tree up which it has chased an animal and positions itself at the base of another tree, barking upward at the branches.
Etymology from Wiktionary, CC BY-SA
Practised in Idioms