From Longman Dictionary of Contemporary Englishbark up the wrong treebark up the wrong treeinformalWRONG/INCORRECT to have a wrong idea, or do something in a way that will not give you the information or result you want The police spent three months barking up the wrong tree on the murder investigation. → bark
Examples from the Corpus
bark up the wrong tree• Can't help thinking that they are on the right track and it's we who are barking up the wrong tree.• Could he once again be barking up the wrong tree?• However, those who advocate a federal takeover of workers' compensation are barking up the wrong tree.• In retrospect it now seems that both camps were barking up the wrong tree.• People who feel sorry for my old bridesmaid and travelling companion are barking up the wrong tree.• They have maybe barked up the wrong tree.• You're barking up the wrong tree if you think Sam can help you. 