Confused about output

[Shane Brandes]

After fiddling with this for hours i cannot figure out why the added
lyrics e and i drop below the bass as opposed to the voices they ought
to be associated with which is here "melody" and "mel" that live on
the soprano staff. What am I missing?

\version "2.18.2"

sopranoVoice =  {
  a2 <<
  \context Voice = melody \relative {
   c'
  }
   \new Lyrics { \set associatedVoice  = #"melody" \lyricmode {
   e }
  }<<
  \new Voice = "mel" \relative {
\stemDown    a2
  }
  \new Lyrics \lyricsto "mel" {\set associatedVoice  = #"mel"
  i
  }
>>
>>
}

verseSopranoVoice = \lyricmode {
  a }

bassVoice = \relative c {
  f e
}

versebassVoice = \lyricmode {
 o u
}

sopranoVoicePart = \new Staff \with {
  instrumentName = "Soprano"

} { \sopranoVoice }
\addlyrics { \verseSopranoVoice }

bassVoicePart = \new Staff \with {
  instrumentName = "Bass"

} { \clef "bass"\bassVoice }
\addlyrics { \versebassVoice }

\score {
  <<
    \sopranoVoicePart
    \bassVoicePart
  >>
  \layout { }

}


regards,
Shane