calibre-server: no library

Hi there, Im running calibre-server 3.0 on archlinux
I tried to start the server using:

calibre-server --port 8001 /path/to/my/flibraryfolder/

If I open the webpage, it says:
"Select library...."
without any other options or possibilities to select a library from a dropdownmenu or something else...

If I start the server without path to my library, it prompts: "no library found" and exits.

So, the path seems to be correct, but somehow no entries are shown. Instead, there is this "Select library...." message on the webpage

What am I missing?

greetings from Germany
Joe