add custom server alias to apache config

[soomon]

hey guys,

I have ispcp 1.0 running on my server with some websites.
i now want to access some of them via my vpn connection to my server so i have a secured connection.
so i added the site name i want it to be accessible at (site.abc) to /etc/apache2/sites-available/ispcp.conf at the part of that website:

ServerAdmin webmaster@abc.de
DocumentRoot /var/www/virtual/abc.de/htdocs

ServerName abc.de
ServerAlias http://www.abc.de abc.de *.abc.de site.abc <--

Alias /errors /var/www/virtual/abc.de/errors/

but after a reaload accessing the site only shows:

Not Found
The requested URL / was not found on this server.

i added site.abc to my windows hosts file.

ports.conf sais:
Listen 80
Listen 443

but wheres my mistake?
or do i have to create a new file and copy everything of that domain but with only that one server name and alias ?

thanks & greets,
soomon