Problem with acciaccatura

[Alberto Corella]

Hi!
I've got a problem with an \acciaccatura. It doesn't work as expected (by me).
I've  read the docs and found something in 6.4.6 about a explicit context voice
but, maybe for my low level english, I can't understand.
The acciccatura is merged with the tremolo instead of be printed before it.
How can I fix it?
Thanks!

Here is my file:

% Created on Sun Jun 25 20:43:45 CEST 2006
\version "2.6.3"

\header {
        title = "Die Lustige Witwe Walzer"
        subtitle = "(La viuda alegre)"
        composer = "FRANZ LEHÁR"
        arranger = "F. W. Meacham"
        piece = "INTRODUCCION"
}


staffPiano = \new PianoStaff {
\set PianoStaff.midiInstrument = #"acoustic grand"
\override PianoStaff.InstrumentName #'space-alist = #'((left-edge extra-space .
2.5))
\set PianoStaff.instrument = #"Piano "
\time 4/4
<<
\context Staff = "RH" {  % Right hand 
\clef treble
\key g \major
\relative c' {
        <g' b d g>4\ff <g b d> <g b e> <g b> |
        \times 2/3 { <c fis, d>4 c8 } \times 2/3 {<c fis, d>8 b a } <a c fis
a>2\arpeggio |
        <a c e a>4 <a c e> <a c fis> <c fis,> |
        \times 2/3 { <d b g d>4 d8 } \times 2/3 { <d b g d>8 c b } <b d g 
b>2\arpeggio |
        <b d e b'>4 <b d e> \times 2/3 { <c e a c>8 b' a } <c, e>4 |
        <a b dis fis>4 <a b> <g b e g>2 |
        <g' b d! g>4 <d g b d> <e gis b e> <b d gis b>|
        <c e a c>4 ~ \times 2/3 {<c e a c>8 <d d'> <e e'>} <b d b'>4.\> a'8\! |
        \bar "||"
        \time 2/4 r4\fermata r8\p <g b,>8->( |
        <fis b,>8 <e b> <d b> <b g>) |
        }
}
\context Staff = "LH" {  % Left hand                    
\clef bass
\key g \major
\relative c {
\acciaccatura g8 \repeat "tremolo" 8 {<d' g>32( b'32)} \repeat "tremolo" 8
{<b g>32( d32)} |
\repeat "tremolo" 8 {<d, fis>32( c'32)} \repeat "tremolo" 8 {<c a g>32( d32)} |
\repeat "tremolo" 8 {<d, fis>32( c'32)} \repeat "tremolo" 8 {<c a g>32( d32)} |
\repeat "tremolo" 8 {<d, g>32( b'32)} \repeat "tremolo" 8 {<b g>32( d32)} |
\repeat "tremolo" 8 {<e, gis>32( d'32)} \repeat "tremolo" 8 {<e, a>32( c'32)} |
\repeat "tremolo" 8 {<b, fis'>32( b'32)} \repeat "tremolo" 8 {<e, g>32( b'32)} |
\repeat "tremolo" 8 {<d, g>32( b'32)} \repeat "tremolo" 8 {<d, gis>32( b'32)} |
\repeat "tremolo" 8 {<d, a'>32( c'32)} <d, fis c'>4 <d d,>4
        d'4->\fermata r8 g->( |
        fis8 e d b) |
                }
                }
        >>
}
\score {
        <<
        \staffPiano
        >>
        
\midi {
        \tempo 4 = 100 
        }

        \layout  {
        }
}

\paper {
}