alternate lyrics + multiple strophes

[Bernd Edler]

Hello,
i have trouble with applying the "alternate lyrics"
technique from repeats.ly (de eerste maat..) from the "tips & tricks"
section of the manual to multiple stanzas.

Instead of:

 Staff==============
 1st stanza 1st (bbb)
 1st stanza rpt.(ccc)
 2nd stanza 1st (xxx)
 2nd stanza rpt.(yyy)


I get.

 Staff==============
 1st stanza 1st (bbb)
 2nd stanza 1st (xxx)
 1st stanza rpt.(ccc)


code:

\version "2.2.4"

\score{
        <<
                  \context Staff \notes\relative c'{
                          c d e f
                          \repeat "volta" 2 { g a b c }
                          \alternative { { c b a g } { f e d c } }
                  }
                  \context Lyrics=A \lyrics {
                      \set stanza = "1."
                          aa aaa- aaa  aaaa
                          \repeat fold 2 { }
                          \alternative {
                                  { bb bbb bbbb bbbb }
                                  { ccc ccc- cccc _ }
                          }
                          dd ddd ddd ddd dd ddd- ddd ddd
                  }
                  \context Lyrics=B \lyrics {
                      \set stanza = "2."
                          ww www- www  wwww
                          \repeat fold 2 { }
                          \alternative {
                                  { xx xxx xxxx xxxx }
                                  { yyy yyy- yyyy _ }
                          }
                          zz zzz zzz zzz zz zzz- zzz zzz
                  }
        >>
}


What am I doing wrong?
If lilypond is doing wrong, then maybe there
is a nice method to work around.
If I use 2 lines of lyrics for each strophe with \skip for
not repeated parts, I get an ugly spacing for lines of score without
repeats.

Thanks,
Bernd Edler