make-span-event

[Juergen Reuter]

Hi!

Maybe this is a silly question, but there is something that I do not quite 
understand.  I am trying to create span events in a music function:


\version "2.4.0"
crescendo = #(def-music-function
               (location music) (ly:music?)
               (make-music 'SequentialMusic
                           'elements (list
                                      (make-span-event 'CrescendoEvent START)
                                      music
                                      (make-span-event 'CrescendoEvent STOP))))

crescendoStart = #(make-span-event 'CrescendoEvent START)
crescendoStop = #(make-span-event 'CrescendoEvent STOP)

\score {
  <<
    { c d\crescendoStart e\crescendoStop f }
    { c \crescendo { d e } f }
    { c d\cr e\endcr f }
  >>
}



In this example, the predefined \cr and \endcr work well; also do the 
locally defined \crescendoStart and \crescendoStop.  However, although the 
\crescendo music function uses exactly the same scheme expressions for 
creating span events, applying the \crescendo function does not show any 
effect.  What I am doing wrong?

Greetings,
Jürgen