One of my book for mac HDs will not mount

Portable Drives My Passport
1

I bought two WD - My Book for MAC hard drives. One works fine - but this one registered above will not mount or show up in any utilities like Disk Utility. WHY? How do I get my MAC to recognize it? I seem to remember when I first bought them it mounted, but only that one time. After that is will not show up.
Have asked by email support but NO reply.

2

Problem solved - ignore this question