Barking up the Wrong Tree

“Barking up the Wrong Tree” is a saying that means to take the wrong approach or waste your efforts. "If you're looking for a job here, you're barking up the wrong tree."

This is an old saying that originates in America and refers to hunting dogs in the early 19th century. Hunted prey such as raccoons or bears would escape the dogs by climbing up trees. The dogs would then track them and hopefully "tree" them and then the dog would sit and bark at the base of the tree, waiting for their master. However, sometimes the dogs would lose the scent and select the wrong tree, but they would still sit and bark there waiting for their master.