Re: programming error: (de)crescendo on items with specified volume.

[Martial]

> You must specified a volume (dynamics) with  logique (de)crescendo

ditto  the midiMaximumVolume and midiMinimumVolume do not equal.

this example return
 programming error: (de)crescendo on items with specified volume.

\score {
 {
\set Staff.midiMaximumVolume = #0.5
\set Staff.midiMinimumVolume = #0.5
   b8 a4.\f\> ^"rit." r8 f8 \! \p  e f
 }
 \midi { }
}