Externe HD Elite no recognition

WD Mybook Elite windows 7 SP1 doesn’t recognise it. no appearance at system, no letter, no recognition anywhere.

USB ports are good, has anyone an idea where the problem could be? cables and electricity are also oke.
thank you already very much

Hi,

Is the drive showing under disk management?

http://support.wdc.com/KnowledgeBase/answer.aspx?ID=1284