Hello,
This is because the "-darkback" module style is only available in the emusica template. You'd have to use this template or just use the "-dark" module style in this template Incline that you are using.
Regards,
thanks. do you mean the "dark style" theme style? there is also no dark background. it looks just like this:
https://www.dropbox.com/s/hf5l6rsp05l59p5/mp3gallery-dark.jpg?dl=0when typing "-dark" in module class suffix nothing happens...