Linux – nginx – 403 Forbidden

I've trouble to get aliases working correctly on nginx.
When i try to access the aliases, /pma and /mba (see secure.example.com.conf), i get a 403 Forbidden but the base url works correctly.

I read a lot of posts but nothing helped, so here i am.

Nginx and php-fpm are running as www-data:www-data and the permissions for the directories are set to:

drwxrwsr-x+  5 www-data www-data 4.0K Dec  5 22:48 ./
drwxr-xr-x.  3 root     root     4.0K Dec  4 22:50 ../
drwxrwsr-x+  2 www-data www-data 4.0K Dec  5 13:10 mda.example.com/
drwxrwsr-x+ 11 www-data www-data 4.0K Dec  5 10:34 pma.example.com/
drwxrwsr-x+  3 www-data www-data 4.0K Dec  5 11:49 www.example.com/
lrwxrwxrwx.  1 www-data www-data   18 Dec  5 09:56 secure.example.com -> www.example.com/

Im sorry for the bulk, but i thought better too much than too little.

Here are the configuration files:

/etc/nginx/nginx.conf

user              www-data www-data;
worker_processes  1;

error_log   /var/log/nginx/error.log;
#error_log  /var/log/nginx/error.log  notice;
#error_log  /var/log/nginx/error.log  info;

pid         /var/run/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    keepalive_timeout  65;

    include /etc/nginx/sites-enabled/*;

}

/etc/nginx/sites-enabled/secure.example.com

server {
    listen          80;
    server_name     secure.example.com;
    return          301 https://$host$request_uri;
}

server {
    listen          443;
    server_name     secure.example.com;

    access_log      /var/log/nginx/secure.example.com.access.log;
    error_log       /var/log/nginx/secure.example.com.error.log;

    root            /srv/http/secure.example.com;

    include         /etc/nginx/ssl/secure.example.com.conf;
    include         /etc/nginx/conf.d/index.conf;
    include         /etc/nginx/conf.d/php-ssl.conf;

    autoindex       off;

    location /pma/ {
        alias       /srv/http/pma.example.com;
    }

    location /mda/ {
        alias       /srv/http/mda.example.com;
    }
}

/etc/nginx/ssl/secure.example.com.conf

ssl                 on;
ssl_certificate     /etc/nginx/ssl/secure.example.com.crt;
ssl_certificate_key /etc/nginx/ssl/secure.example.com.key;
ssl_protocols       SSLv3 TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers         HIGH:!aNULL:!MD5;

/etc/nginx/conf.d/index.conf

index   index.php index.html index.htm;

/etc/nginx/conf.d/php-ssl.conf

location ~ \.php$ {
    try_files       $uri =404;
    fastcgi_pass    unix:/var/run/php-fpm/php-fpm.sock;
    fastcgi_index   index.php;
    fastcgi_param   HTTPS on;
    fastcgi_param   SCRIPT_FILENAME  $request_filename;
    include         fastcgi_params;
}

/var/log/nginx/secure.example.com.error.log

2013/12/05 22:49:04 [error] 29291#0: *2 directory index of "/srv/http/pma.example.com" is forbidden, client: 176.199.78.88, server: secure.example.com, request: "GET /pma/ HTTP/1.1", host: "secure.example.com"

EDIT: forgot to mention, i'm running CentOS 6.4 x86_64 and nginx 1.0.15

Thanks in advance!