Subdomain is loading pages from parent domain

[BradMathews]

I created a subdomain using the physical hosting option. This created a new folder: vhosts/mydomain.com/subdomains/mysubdomain/httpdocs/

I moved my files into the httpdocs folder and pointed my browser to the subdomain. But I am being served the files in my domain parent folder (vhosts/mydomain.com/httpdocs/)

This is certainly not what I expected!

To be clear: http://www.mydomain.com is serving the exact same file as http://subdomain.mydomain.com

How do I get this subdomain pointing at its own folder?

I have Plesk 9.0.1 on Windows Server Web SP2. This is a co-hosted, not virtual, server.

Thanks!
Brad