Hairpin movement??

[Steve Shorter]

Howdy!

        I'm trying to move a hairpin verticaly using 'extra-offset'.
I looked at the mail archives and concluded that the simple example
below should work, but it doesn't. 

        Any ideas why? What is the best way to move a hairpin?


one =   \context Voice=one \notes \relative c'' {
        \voiceOne
        \clef treble
        \time 3/4
        \stemUp
        d2.
}

two =   \context Voice=two \notes \relative c' {
        \voiceTwo
        \clef treble
        \time 3/4
        \stemDown
        \property Voice.Hairpin \override #'extra-offset = #'(0 . -3.5)
        d2\< d4\!
}

\score {
        \notes \context Staff = treble <<
                        \key d\major
                        \one
                        \two
        >>
}