On a cPanel server if you get the error: Error from park wrapper: domain.com is already configured while adding an add-on domain under cPanel. Make sure to remove the domain.com entries from:
/var/named/domain.com.db
/etc/httpd/conf/httpd.conf
/usr/local/apache/conf/httpd.conf
/var/cpanel/users/username
/etc/userdomains
/etc/groups
/etc/localdomains
Renaming or commenting will not help; you will have to remove the entries completely. Try now.
This worked for me.
source:
http://supportfacility.com/blog/cpanel/error-from-park-wrapper-domaincom-is-already-configured/