FTP account ownership on vhost directory makes Apache not run website correctly

view story

http://serverfault.com – I've purchased a virtual server, where I'm given of a non-root sudo-enabled user. Actually I do need to create an FTP account that's not that sudo-able account, so I created a no-login account just for that purpose. I've set up VSFTPd correctly, also enabling the "userlist" feature, to specify which user are permitted to use FTP. Then I created an empty directory under my sudo-able account, and I gave ownership permissions to the second account, so to make it more easy to understand, let's say the main account (the one I do use to manage my VPS) is called ubuntu and the FTP-user is named ftp (HowTos)