nginx定向代理问题

######nginx.cnf

    server {

                listen          80;

                server_name     www.xx27.net xx27.net;

               include vhosts/upstream.cnf

                location / {

                        proxy_redirect          off;

                        proxy_set_header        Host $host;

                        proxy_set_header        X-Real-IP $remote_addr;

                        proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;

                        client_max_body_size    10m;

                        client_body_buffer_size 128k;

                        proxy_connect_timeout   90;

                        proxy_send_timeout      90;

                        proxy_read_timeout      90;

                        proxy_buffer_size       4k;

                        proxy_buffers           4 32k;

                        proxy_busy_buffers_size 64k;

                        proxy_temp_file_write_size 64k;

                        proxy_pass      http://www.xx27.net

                }

#####upstream.cnf

       upstream www.xx27.net {

                server 192.168.8.1:3128 weight=5;

                server 192.168.8.2:80   weight=1;

                server 192.168.8.3:80   weight=6;

        }

上面是我的配置,但是怎么调试都无法正确代理到后端服务器,而是全部访问www.xx27.net这台服务器,也没有报错,这是什么情况,如何查看upstream是否生效呢