Domain Mapping failed - Just shows 'Welcome to Nginx' page

Hi,

I have some problem with domain mapping.

I want to change domain junq.mytrenz.com to smoothiefast.com. Registering the new domain name on dashboard was succeed, but the new domain just shows 'Welcome to Nginx' page. And on dashboard, its health status shows 'Invalid' status.

I setup the server with EasyEngine and using Domain Mapping plugin.
And DNS is digitalocean.com.

Also, I tried to change the config file named 'nginx.conf' following steps from page : https://rtcamp.com/wordpress-nginx/tutorials/multisite/subdomains/minimal/ but it did not work. Actually, there is no 'server {.......}' code in my config file originally.

So, I cannot find my way out.

Any suggestions or comments are very welcomed. Thanks!