Partition fails on new passport due to 'invalid request'

Hi, I have a brand new, unused My Passport Ultra 3.0. I need to use it to back up my mac desktop and a windows laptop. following the WD instructions, I use the disk utility, select Master Boot Record and I get to the partition window, fill in as directed for 1 partition, but get a Partition failed due to Invalid Request. help appreciated thanks.


Instead of “Master Boot Record” try using “Apple Partition Map” and try again. Let me know how it goes.

Take a look at this link for more information.