缓存 expires问题,求大神指教

在nginx中已设置
server{
listen 80;
server_name static.commao.com;
index index.html index.htm index.php;
root /home/web/commaoSite/v2.0.5/img.commao.com;
location ~ .*.(gif|jpg|jpeg|png|bmp|swf)?$
{

            expires      30d;
    }

    location ~ .*\.(js|css|svg|eot|ttf|woff)?$
    {


            expires      12h;
    }

    access_log  /home/wwwlogs/staticcommao.log  access;

}

但浏览器中Cache-Control:"max-age=0" 是怎么回事

location ~ .*\.(gif|jpg|jpeg|png|bmp|swf)?$

点号没转义

expires 控制的返回的头中的Expires，而且返回304已经表明cache生效了
Cache-Control需要通过 http://www.cnblogs.com/jason-zy/archive/2012/03/06/2381433.html