Certificate Template Subject Name built from AD

Hi,

I have configured a certificate template to build from AD and have chosen Common Name for subject and DNS name for the SAN. I was hoping that choosing Common Name that I would get what is in the CN field of the AD object (in this case a computer account). This seems to be alluded to in this article:

http://technet.microsoft.com/en-us/library/cc753994.aspx

But after configuring the template in this way, the issued certs have a Subject Name that reads:

CN = computername.mydomain.local

And a SAN that reads:

DNS = computername.mydomain.local

Why is this happening?