cross staff bug?

[Kieren MacMillan]

Hi all,

Can anyone explain why this snippet (from Beethoven Op. 10 No. 3) is failing in 
two different ways?

\version "2.17.19"
\language "english"

piano_notes_upper = \relative d' {
  <d fs d'>4 r r \crossStaff { r8 <d d,>8 }   | % 16
  \crossStaff { r8 <cs cs,> r <b \parenthesize b,> r <a \parenthesize a,> r <cs 
cs,> }   | % 17
}

piano_notes_lower = \relative d, {
  \clef bass
  <d d'>4 r r d-.   | % 16
  cs4-. b-. a-. cs-.   | % 17
}

\layout {
  \context {
    \PianoStaff
    \consists #Span_stem_engraver
  }
}

\score {
  \new PianoStaff <<
    \new Staff << \key d \major \piano_notes_upper >>
    \new Staff << \key d \major \piano_notes_lower >>
  >>
}

1. It's not cross-staffing; and,
2. The eighth-note flags are not appearing.

Thanks,
Kieren.