Using pianostaff with custom created percussion staffs

[lilypond]

Hello (Kieren ?)

I could create custom Staff's now, thanks to the help of Kieren. And  
use separated Voices within it.

Now there are two different percusion instruments (African DunDun and  
SangBang) which should be played with one person. A PianoStaff would  
be ideal for this.

I could use the PianoStaff succesfull when I defined the Staff and the  
Voice together. But I wanted to separated them for more structure.

Could someone say what I did wrong?

\score {
  \new StaffGroup {
  <<
    \tempo 4=100
    % \new PianoStaff
     \new TwoLineStaff \new Voice \DunDunVoice
     \new TwoLineStaff \new Voice \SangBangVoice

  \new DjembeStaff \new Voice \DjembeIVoice
  \new DjembeStaff \new Voice \DjembeIIVoice
  \new DjembeStaff \new Voice \DjembeIIIVoice
> >
}
  \layout { }
  %  \midi { }
}

Thanks,

Bernard

Addition :
If needed below is the definition of the Staffs and some voices. Of  
course original this is defined first.


Custom Staff definition :

\layout {
  \context {
    \Staff
    \name DjembeStaff
    \alias Staff
    clefGlyph = #"clefs.percussion"
    clefPosition = #0
    \override TimeSignature #'style = #'numbered
    \override StaffSymbol #'line-count = #3
  }
  \context {
    \Staff
    \name TwoLineStaff
    \alias Staff
    clefGlyph = #"clefs.percussion"
    clefPosition = #0
    \override TimeSignature #'style = #'numbered
    \override StaffSymbol #'line-count = #2
  }
  \context {
    \Score
    \accepts DjembeStaff
    \accepts TwoLineStaff
  }
}

Custom voice definition :
DunDunVoice =
\relative c' {
  % \time 3/4
 \set Staff.instrumentName = #"Dundun (R)"
 {  g'1 r1 g2 g2 r1  \bar "|."
 }
 }

SangBangVoice =
\relative c' {
  % \time 3/4
 \set Staff.instrumentName = #"Sang Bang (L)"
 {    r1 g'1 r1 g1
   \bar "|."
 }
 }