Problem with \slashedGrace and \partial

[Pieter Terpstra]

Dear Readers,
Have some issues here.

Stem goes down here (even if i try a \stemUp) and get double crosses and time 
signature.

What goes wrong here?

Thank you again so much!

Peter

score:
\version "2.18.2"

global = {
  \key a \major
  %\defaultTimeSignature
  \time 2/4
}

CGVoiceOne = \relative c' {
  \global
  \partial 8 \slashedGrace fis8 e16. dis32\p |
  e8 a a \slashedGrace fis8 e16. dis 32 |
}
CGVoiceTwo = \relative c {
  \global
  \partial 8 r8 |
  r a [a] r | 
}
\score {
   \new Staff \with {
    midiInstrument = "acoustic guitar (nylon)"
  } { \clef "treble_8" << \CGVoiceOne
                          \\ \CGVoiceTwo >>
}}