log file empty

[Cos]

Dear All

My system is FreeBSD 9 with latest version nginx.

Here is my conf file content:

#user  www;
worker_processes  1;

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

#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}

The problem is I can not see anything from /var/log/nginx-error.log,
all error logs outputed to screen directly.

I have tried specify error_log directory or user account. But same..

Please suggest.

-- 
with kind regards