subdomain Multisite doesnt work because WordPress URL contains a path

Hi,
For testing i want to check the Multiste behaviour.

I have a domain indien-schmuckkunst.com

And unter /test there is the Test WP.
If i call http://www.indien.schmuckkunst.com/test i can show the blog.
On the server the blog is installes unter /www/test
(When i got there with a FTP Client)

If i enable Multisite under the Network Configuration Panel there is NO option for subdomains.
I found in codex:
You cannot choose Sub-domain Install (for a domain-based network) in the following cases:

The WordPress URL contains a path, not just a domain. (That is, WordPress is not installed in a document root, or you are not using the URL of that document root.)

SO what possibilities do i have ? If changing the WP URL i cannot login anymore (sounds strange but it happens)

What must i change so that i can use a subdomain?
best ahmed