No more space between key signature and notes ?! problems with pedal voice

[MX]

Hi all,

I try to lilypond a choral for organ of J.S. Bach with a pedal voice.

In the following picture, you can notice that there is no more space 
between the key signature and the first notes of every line.

During the compilation I have the following warning : "Programmation 
error : adding reverse spring, setting to unit."

The problem disappears when I put off the pedal voice.

Is it a bug or a misunderstanding of the Staff command ?

Thank you in advance.

M.X.

% -*- mode: LilyPond ; coding: utf-8 -*-
\version "2.6.4.3"
\include "italiano.ly" 

\header{
    title =  "Vor deinen Thron tret' ich." 
    subtitle = ""
    piece = "" 
    instrument = ""
    composer = "Johann Sebastian Bach (1685-1750)"
    copyright = "Creative Commons Attribution-ShareAlike 2.5"
    source = "Bach-Gesellschaft Edition OrgelWerke Bd 4. 1893"
    opus = "BWV 866"
    lastupdated = "2006-02-26"
    enteredby = "Gérard Gréco"
    maintainer = "Gérard Gréco"
    mutopiatitle = "Vor deinen Thron tret' ich"
    mutopiacomposer = "BachJS"
    mutopiainstrument = "Organ"
    style="Baroque"
    footer = ""
    tagline = ""
}

#(set-default-paper-size "a4")
%#(set-global-staff-size 20)

halsup = {
  \stemUp
  \tieUp
}

halsdown = {
  \stemDown
  \tieDown
}

staffup = {
   \change Staff = "dessus" \halsdown
}

staffdown = {
   \change Staff = "basse" \halsup
}



global = {
  \key sol \major
  \time 4/4
}

choral =  \relative do'' {
  \global \halsup
  \override MultiMeasureRest #'staff-position = #2 R1
  \override MultiMeasureRest #'staff-position = #4 R1*4
  \override MultiMeasureRest #'staff-position = #2 R1*1
 
}

alto = \relative do'' {
  \global \staffup
  \override MultiMeasureRest #'staff-position = #-2 R1 
  sol8\rest sol8 sol8 fad8 mi4 fad8 mi8 
  re8 mi8 fad4 sol4. fad8 
  mi8 [ la8 ] re,8 sol8 ~ sol8 fad16 mi16 fad8 sol8 
  %  5 : ================
  la4 sol8 la8 si8 re,8 [ re8 dod8 ] 
  \staffdown si4 dod8 si8 la8 si8 dod4 
}

tenor = \relative do' { 
  \global
  %  1 :
  \tieDown \stemDown r8 sol8 sol8 la8 si4 la8 si8 
  do8 si8 la4 sol8 sold8 la8 lad8
  si4. la!8 si8 dod8 re4 ~
  re8 do!8 si8 mi8 la,2 ~
  %  5 : ================
  la8 si8 do4 si8 la8 sol4 ~
  sol8 fad8 sol8 sold8 \dotsDown \once \override Staff.NoteCollision 
#'merge-differently-dotted = ##f la4. \dotsNeutral sol8 
}

pedale = \relative do {
  \global
  \clef bass
  % 1 :
  R1*3 \break
  r2 r8 re8 re8 mi8 
  %  5 : ================
  fad4 mi8 fad8 sol8 fad8 mi4 
  re8 red8 mi8 mid8 fad4. mi8 

}

\paper {
  betweensystempadding = 1\mm
  betweensystemspace = 1\mm
  %raggedbottom = ##f
  %raggedlastbottom = ##f
  headsep = 1\mm
  %aftertitlespace = 1\mm
  indent = 1\cm
  bottommargin = 4\mm 
  topmargin = 4\mm
}

\score {
  {
   
      \context PianoStaff <<
        \context Staff = "dessus" <<
          \global
          \clef violin 
          \set Staff.midiInstrument = "pan flute"
          \choral
        >>
        \context Staff = "basse" <<
          \global    
          \clef bass
          \set Staff.midiInstrument = "pan flute"
          \alto
          \tenor
        >> 
        \context Staff = "pedale" <<
          \global
          \clef bass
          \pedale
        >>
      >>
   
  }
  \layout {}
  \midi{ \tempo 4 = 100  }
}