pdf not working in book library

[zelpi]

I created a book type library and scanned my pdfs in Jellyfin media player. The folders in Jellyfin appear according to the structure on Windows, which is ok. But when opening a detail page - how can I display the pdf? I can only see the button which in movie library starts the video. When I click in the book library on it, nothing is displayed, only the loading sign shows up. What am I doing wrong?