barking up the wrong tree
US /ˈbɑːrkɪŋ ʌp ðə rɔŋ triː/
UK /ˈbɑːrkɪŋ ʌp ðə rɔŋ triː/

1.
找错了对象, 弄错了
to be pursuing a mistaken course of action or to have a wrong idea about something
:
•
If you think I stole your pen, you're barking up the wrong tree; I haven't seen it.
如果你认为我偷了你的笔,那你就是找错了对象;我没见过它。
•
The police were barking up the wrong tree when they suspected the innocent man.
警方怀疑无辜男子,是找错了对象。