Domain and its subdomain

[Cube]

I would like to add a user example.org and a user sub.example.org in ispcp. This works without problems, but example.org it matched first by Apache, so always the example.org website is shown. The apache2 -S command also shows example.org before sub.example.org. This is probably because the example.org entry is written first into the apache configuration.
Any suggestions how to solve this?