Barking Up the Wrong Tree

A literal image from American frontier raccoon hunting. Hunting dogs would chase their quarry up a tree, then stand at the base barking to alert their owner, except raccoons are agile enough to leap between trees, so the dog was sometimes barking at an empty tree while the raccoon had already escaped through the branches overhead. The phrase is recorded in American English from the early 1830s and crossed into everyday figurative use soon after.