Partcombine and Lyrics

[Johan Vromans]

Hi,

Basically, I've got something like this

  <<
    \new Staff = smed <<
      \new Voice = "med"  {
        \medMusic
      }
    >>
    \new Lyrics = med { s1 }
    \context Lyrics = med \lyricsto med \medWords
  >>

Now I want to add a second melody. It's identical to the first, with a
few exceptions. So I want to use partcombine.

  <<
    \new Staff = smed <<
      \new Voice = "med"  {
        \set Staff.printPartCombineTexts = ##f
        \partcombine \medMusic \lowMusic
      }
    >>
    \new Lyrics = med { s1 }
    \context Lyrics = med \lyricsto med \medWords
  >>

However, now Lilypond complains "cannot find Voice 'med'".

How can I add lyrics to combined parts?

Thanks,
        Johan