solo series

[Ferenc Wagner]

Hi,

why do I get two empty measures between the solos in the
following snippet?  How should I do this?  I'd like to keep
the corresponding notes and lyrics together.  In the output:

programming error: Moving backwards in time
Continuing; crossing fingers

Thanks,
Feri.

\version "2.2.1"

\include "deutsch.ly"

\score {
    \new Staff
    {
        <<
            \context Voice = "sopr" \notes \relative c' {
                c4 d e8 f g4 a h c2
            }
            \context Lyrics \lyricsto "sopr" \lyrics {
                c d e f g a h c
            }
        >>
        <<
            \context Voice = "alto" \notes \relative c'' {
                c4 h a8 g f4 e d c2
            }
            \context Lyrics \lyricsto "alto" \lyrics {
                c h a g f e d c
            }
        >>
    }
}