WD will not switch of

I have three WD external drives and one will not swith of when I switch my computer of, even if the computer is of and I turn the power of to the WD it still keeps running. I have tried pushing the button in the middle but it is naughty and just will not switch of. Any ideas please?

Hi there, what if you post the model number of the drive? Some of them have a sleep timer you can program!