Chances are the URL for the domain may be entered incorrectly in the settings of the Splash page.
To check, head to the Settings tab of your event page's toolbar.
If you have http:// or www. (or both) in the Vanity URL, go ahead and remove it. It's not necessary! Click save, and you'll be all set.
Note: We do not support custom URLs formatted differently than domain.com or subdomain.domain.com (ie. domain.com/custom or subdomain.domain.com/custom).