Apache Clustering via mod_proxy_balancer

I am using a load balancer to server a cluster. I can't get it to function.

LoadModule authz_host_module    modules/mod_authz_host.so
LoadModule mime_module          modules/mod_mime.so
LoadModule dir_module           modules/mod_dir.so
LoadModule log_config_module    modules/mod_log_config.so
LoadModule alias_module         modules/mod_alias.so
LoadModule setenvif_module      modules/mod_setenvif.so
LoadModule proxy_module         modules/mod_proxy.so
LoadModule ssl_module           modules/mod_ssl.so
LoadModule headers_module       modules/mod_headers.so
LoadModule proxy_connect_module modules/mod_proxy_connect.so
LoadModule proxy_http_module    modules/mod_proxy_http.so
LoadModule proxy_balancer_module modules/mod_proxy_balancer.so

    RequestHeader set X_FORWARDED_PROTO 'https'
    ProxyPreserveHost on
    <Proxy balancer://redminecluster>
           BalancerMember http://127.0.0.1:3000
      #     BalancerMember http://127.0.0.1:3001
      #     BalancerMember http://127.0.0.1:3002
    </Proxy>
    ProxyPass / balancer://redminecluster
    ProxyPassReverse / balancer://redminecluster

The above code serves a mobile looking page with CSS styles broken, and internal server errors when navigating to pages. This works fine if I comment all the proxy lines above:

ProxyPass / http://127.0.0.1:3000/
ProxyPassReverse / http://127.0.0.1:3000/

Any ideas?