Looking at the tutorial,
Do you have a line that looks like this?
try_files $uri $uri/ index.php;
This will attempt to serve the file specified by the URI in relation to
alias). If the file is not found
nginx will then redirect you to index.php.
I hope this helps, but we must be missing something...
I'm assuming you've tried restarting Nginx (
sudo service nginx
restart). Nginx won't read the configuration files until you do
sudo service nginx reload).