Trouble formatting My Book Essential 2TB for Mac

WD External and Portable SSD External SSD for macOS
1

Just bought External HD and trying to format for Mac so I can saves videos from iMovie.

Went to the Disk  Utility, set Volume Scheme: 1 Partition, Option: GUID Partition Table, Format: Mac OS Extended (Journaled).

When I clicked Apply, I got message, “Partition failed with error.  Could not unmount disk.”

I’ve got a MacBook Pro with 2.4 GHz Intel Core 2 Duo running Mac OS X Version 10.5.8.

I’m not very computer savvy but I got my formatted a LaCie external drive without much effort.  Am I doing something wrong or should I be concerned about the condition of the drive?

Thanks in advance!

2

I don’t know about Macs but maybe this will help http://wdc.custhelp.com/cgi-bin/wdc.cfg/php/enduser/std_adp.php?p_faqid=3865  Most of us don’t formatt or partition that often so it’s easy to miss something simple.

Joe