Barking Up The Wrong Tree ( looking for something in the wrong place ... )

When you are looking for something that is not where you are looking, you are "barking up the wrong tree." Example: "I know you think I stole your umbrella. But really, I don't have it. You are barking up the wrong tree."

You are like a dog that is barking up at a tree that has nothing in it. This may also mean trying to find the answer to some problem by using the wrong approach. Example: "I have been trying to solve this one problem for an hour. I really do not know how to do it." Reply: "Yes, I can see that. You've been barking up the wrong tree."

You are "barking up the wrong tree" when you are trying to find something, but you are looking in the wrong place