Voice Context Continuing After Lyrics Were Added and Ended

[Christian Eitner]

Hello,

I'm having trouble understanding how a voice to which lyrics were
added is continued after the lyrics. Here is my snippet:

\version "2.12.2"

\new Staff {
        \new Voice = melody {
                a'1
        }
        <<
        \context Voice = "melody" {
                b'1
        }
        \new Lyrics \lyricsto "melody" {
                Ahh
        }
        >>
        \context Voice = "melody" {
                c'1 d1
        }
}

Instead of c'1 d1, only two empty bars appear.

Thanks for your consideration,

Christian