Any idea why we can't seem to map the primary domain? Just

Any idea why we can't seem to map the primary domain? Just EveryoneGoesHome.com but not FireHero.org .. seems to work but curiousif any impact..trying to get Membership plugin to work

http://www.firehero.org/wp-admin/network/settings.php?page=domainmapping_options&tab=mapped-domains