Domain Mapping - getting server side 404 error

Hello - I'm trying to map to and am getting a server side (where I host 404 error.

I've moved sunrise.php, edited wp-config.php, added DNS A record to and added to 'Domain Mapping'. The 'Domain Mapping' Health Status shows 'valid'. I have a dedicated IP address, wildcard is setup properly... I'm at a loss. Any help is appreciated.