Artist with dead entries

[<moonkid posteo org>]

I try Rygel on a Lubuntu 14.04.2.
Can not tell you a version umber because "--version" only print out the
name "Rygel" - nothing more.

It show my music files correct in the folders All, Genre, Year.
But "Artists" (german: "Künstler") make a problem.
There are entries for all artists. But they are just entries. They are
not tracks I can play and not folders I can enter. Don't know what this
entries are there.

What can I do?