Originally Posted by till
Open the ispconfig database with phpmyadmin, go to the table sys_user and open the record with the username = admin. The field modules must contain this:
Save the changes in the database and the invoicing module must appear after a re login in ispconfig.
isp_fakt was indeed missing, so I added it and logged in again. However, I still wasn't able to see the invoice module. I then ran the setup again and after the "upgrade" the module was visible.Thank you for your help!