My last hint: I installed eLuna in /var/www/eluna but I just noticed that the README.english of my eLuna version 1.07 proposes to install in /var/www/graphs. I changed the name because there is one more graphs directory below. Of course cron and Apache2 must be tolld the exact name of the directory you choose. And maybe my earlier chown command to give ownership of all eluna files to www-data must be adapted too ...
