Barking up the wrong tree

Meaning:	Following a dead end path, pursuing an incorrect lead or assumption.
Example:	If you think those gloves will convict OJ, you are barking up the wrong tree.
Origin:	When using dogs in a foxhunt, the dogs sometimes corner the fox in a tree. The dogs will proceed to bark up at the fox. Barking up the wrong tree, where there is no fox, is a pointless exercise.

Tags: Idioms, Sayings, Word Origins, Words, proverbs