Unable to open "/dev/disk#": 16

I am trying to use this kb as a guide to create a 200G raw vmdk.

This is the command that is not succeeding:

/Applications/VMware\ Fusion.app/Contents/Library/vmware-rawdiskCreator print /dev/disk11

The error message is

Unable to open "/dev/disk11": 16

diskutil list confirms this is what I want:

/dev/disk11 (virtual):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:                  Apple_HFS VM Data                +958.8 GB   disk11

What is error 16, and why am I getting it?

What can/should I do to resolve it?