Adding a rails app to a subdomain

I'm trying to add a separate rails app to my existing rails app running on apache.

I followed the steps at this site (http://blog.codahale.com/2006/06/19/ time-for-a-grown-up-server-rails-mongrel-apache-capistrano-and-you/)

so my setup looks like this

/etc/apache2/http.conf

NameVirtualHost *:80

<Proxy *>   Order allow,deny   Allow from all </Proxy>

#gawkk main site Include /etc/apache2/conf.d/gawkk/gawkk.conf Include /etc/apache2/conf.d/gawkk/gawkk.cluster.conf

#blog Include /etc/apache2/conf.d/blog/blog.conf Include /etc/apache2/conf.d/blog/blog.cluster.conf

each of the sites have their own common file(i'm not sure if that's the way it was suppose to be or not)

in the common file they have

  ServerName blog.myapp.comm   DocumentRoot /var/www/blog/current/public

  RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f   RewriteRule ^/(.*)$ balancer://blog_cluster%{REQUEST_URI} [P,QSA,L]

  ServerName www.myapp.comm   DocumentRoot /var/www/myapp/current/public

  RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f   RewriteRule ^/(.*)$ balancer://myapp_cluster%{REQUEST_URI} [P,QSA,L]

depending on which site i put first in the http.conf that cluster pulls all the requests.

I can't seem to find a way to separate the domain and subdomain apart so that each cluster pulls the request.

Any help would be MUCH appreciated!