Just one more thing I found out:
The engine(s) cannot handle special characters in the path names, even when
they do not appear in a relative path. I had a subfolder ./Exemples with the
Lilypond files, but the path further up contained french special characters, so
I ran into «file not found» troubles.
[...]
Have a great time,
Dona
P.S: I'd like to apologize for the initial flood of messages, it actually took
several hours for my first post to get through, so I kept trying… Maybe adding
a little waring on the mailing list website would be helpful, like: «first
posts may take longer because they are moderated»