Nginx unknown directive "proxy_pass"

I'm having a problem with nginx configuration.

When I set the configuration like this:

 server {
         server_name redmine;
        listen       80;

        location / {
           proxy_pass http://172.16.0.70:33000;
        }
}

I get this error nginx: [emerg] unknown directive "proxy_pass".

My nginx version is nginx/1.8.0.

Someone know what i'm missing or what i'm doing wrong? Thanks.