Dynamic subdomains for author archive

Hi,

I’m currently trying to create dynamic subdomains for each users post page, for example:

bob.wpsite.com
fred.wpsite.com

I have created the dns entries and done all of the server side coding which you can currently see working at:

http://bob.afcnews.com/

The last part I need to work out is the last line of the mod_rewrite in .htaccess, I currently have:

RewriteCond %{HTTP_HOST} !^www\.afcnews.com
RewriteCond %{HTTP_HOST} ([^.]+)\.afcnews.com
RewriteRule ^(.*)$ test.php?url=%1

Which redirects any subdomain apart from www. to test.php?url=username

How can I make the mod_rewrite to point to /author/username/

When I try:

RewriteRule ^(.*)$ author/%1/

It fails and I’m unsure why?