pagebreaks with 2.4.2

[Jean-marc LEGRAND]

Dear list ,

Even if there has been several discussions upon this subject, I still don't 
understand how to use
\pagebreak.

When I moved to 2.4.2 on XP, I converted my 2.2.5 .ly and the \newpage within 
the header block in my
main .ly became \\page break :

\version "2.4.0"
#(set-global-staff-size 16)
\header {
  title =   "MESSE POUR LES INSTRUMENTS"
  subtitle = "au lieu des orgues - H.513"
  composer = "Marc-Antoine CHARPENTIER (1643-1704)"
      }

\include "01.ly"
\score      {
                  <<
                  \context Staff ="1er dessus" \dessusI
                  \context Staff ="2ème dessus" \dessusII

                  \context Staff ="taille" \taille
                  \context Staff ="basse" \basse
                  >>

                  \header {piece="\\pageBreak \\textit{\\textbf{Premier kyrie} 
{pour tous les
instruments}}"}
                  \layout {interscoreline = 0.0
                        interscorelinefill = 1.0
                        textheight= 28.0 \cm}
 }

 But the pagebreak doesn't work anymore.

I've tried another script, from the tip and tricks :

\version "2.4.0"
\header {title = "Title"}
pattern =  { a b c d }
\book {
    \score {
      \context Staff  \relative c' {
          \pattern
         \pageBreak
         \pattern
          }
    }
This one is OK

So I tried to put several score within a sigle book, with pagenreak between 
them :
\version "2.4.0"
\header {title = "Title"}
pattern =  { a b c d }
\book {
    \score {
      \context Staff  \relative c' {
            \pattern
            \pageBreak
             }
          }

\score {
      \context Staff  \relative c' {
          \pattern
            }
    }

This one doesn't wok.
It seems that \pagebreak works only inside the note block.

I'de like to know how to force a page break between different movements in the 
book score, and not
within the notes themselves.

I must admit that on this point, the manual is not very helpfull for me...

Any help ?