loadbalancing is not well.. loadbalancing.

[James]

Ok here's my config slightly changed for security reasons.

http {

     upstream sitemain {
         server 192.168.0.1:80;
         server 192.168.0.2:80;
     }

     server {
         listen 80;
         server_name prod2.site.com;
         location / {
             proxy_pass http://sitemain;
         }
     }
}

If I go to prod2.site.com I get my site, great so it seems to be  
working.  If I stop the apache server on the 192.168.0.80 machine I get

502 Bad Gateway nginx/0.6.31

Any idea on what I am missing to get it to start reading from  
192.168.0.2?

Thanks,
James