Creating Subdomains with a Script

[wptonline]

We need a subdomain for a lot of domains we are hosting. I tried with subdomainmng

/opt/psa/admin/bin/subdomainmng --create --subdomain-name=preview --vhost-name=mycooldomain.de --user-name=mycooldomain-de --cl-id=1

The script creates the subdomain and the files, but it is not listed in Plesk nor the needed files in conf/ are created. What is missing or what do I do wrong?