Magento – Magento Admin Nginx 404

I am migrating from Apache to Nginx magento. The site works fine but when I try to access the admin generates a 404.

www.mydomain.com/admin

This is the configuration that I have on my server

server {
    listen  80;
    server_name www.mydomain.com;
    root /home/mydomain/public_html;
    index index.php index.html index.htm;
    keepalive_timeout 300;
    access_log   logs/access.log;
    error_log    logs/error.log;
    location / {
        if (!-e $request_filename) {
                rewrite ^/([^?]*)(?:\?(.*))? /index.php?title=$1&$2 last;
        }
        if ($uri ~* "\.(ico|css|js|gif|jpe?g|png)(\?[0-9]+)?$") {
                expires max;
                break;
        }
    }
    location ~* \.(jpg|jpeg|gif|png|css|js|ico|xml)$ {
            access_log        off;
            log_not_found     off;
            expires           30d;
    }
    location ~ .php/ {
        rewrite ^(.*.php)/ $1 last;
    }
    location ~ .php$ {
        if (!-e $request_filename) { rewrite / /index.php last; }

        expires        off;
        fastcgi_pass   unix:/tmp/php.sock;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        fastcgi_param  MAGE_RUN_CODE default;
        fastcgi_param  MAGE_RUN_TYPE store;
        include        fastcgi_params;
    }
    location /nginx_status {
            stub_status on;
            access_log   off;
            deny all;
    }
    location /RequestDenied {
            return 500;
    }
    if ($bad_method = 1) {
            return 444;   
    }
}

Versions

1. Nginx/1.4.1
2. Magento 1.8
3. MySql 5.1.73