With nginx; cannot find mysql loggin

I have nginx installed.
Because of a mysql error "Fout tijdens het maken van de databaseverbinding" == error making database connection I was looking for the logging of mysql.
After moving a site (wordpress) and correcting everything in the wp-config.php, I have this error.
The /var/log/mysql.log is "0"
Do I have to put the logging on? Where/how?
Ideas?

 

Is the php_mysql module installed? You can check this with phpinfo();