I have a 'subdomain' install of wpmu with 3 different domain on the same host. I've installed Domain Mapping and Simple Multi-Sites plugins and parked domain-2.com and domain-3.com
what I can't figure out is how I can create a sub-blog under a parked domain that I mapped to have a url: http://blog.domain-2.com.
Please help, I can't get over this hump in my set-up so I can finally focus on blogging.