Full measure rest cadenza

[Philippe Auclair]

Hello,

According to the notation reference
(http://lilypond.org/doc/v2.18/Documentation/notation-big-page.html)
the function mmrest-of-length should print a full measure rest of 
determined length.
However the following construction doesn't work. It does work with 
skip-of-length.

Any idea?

\version "2.18.2"
\language "italiano"

Cadenza_xxiii = { s2. s2. s4. }

HeleneMusic_xxiii = \relative do'' {
        \autoBeamOff

        \time 6/8
        \key mi \major
        \cadenzaOn
        #(mmrest-of-length Cadenza_xxiii)
        \cadenzaOff
        fa2.^\f
}

CalchasMusic_xxiii = \relative do' {
        \autoBeamOff
        \clef bass

        \time 6/8
        \key mi \major
        \cadenzaOn
        r8 r16 <mi mi,>16 <mi mi,> <mi mi,> <mi mi,>4 r8
            r4 <mi mi,>8 <mi mi,>4 r8
            r4 r8
        \cadenzaOff
        \bar "|"
        R2.
}

\score {
   <<
        \new Staff = "Helene" \new Voice = "Helene" {
            \HeleneMusic_xxiii
        }
        \new Staff = "Calchas" \new Voice = "Calchas" {
            \CalchasMusic_xxiii
        }
   >>

  \layout {}
}

Regards,
Philippe