404 on subdomain addons with hostgator

I’m on hostgator shared hosting with WordPress install on an addon domain. Wildcard subdomains are enabled with the document root at the main site public_html folder. Addon domains were put on top of the main subdomain per (http://support.hostgator.com/articles/cpanel/how-to-park-a-domain-on-an-addon-domain).

I’m using WordPress MU Domain Mapping Plugin. Main site shows up, additional sites give 404 error. Thanks for helping me figure out what I missed. Main site is at http://www.sparkspress.com.