POSTFIX to use Admin

Scratching my head badly... The maillog of POSTFIX saying error delivering error.
And the error always persist if email to `admin` user. After googling and found this.
Telling to check the /etc/aliases. Yes it has
admin: root
security:   root
hostmaster: root
marketing:  postmaster
sales:      postmaster
support:    postmaster

So i only removed the admin line. Restart the postfix and it works.
The email sent to admin@mydomain is well received.

Hope that helps ^^