Trouble with acciaccatura at the beginning of a piece

[Ninn Langel]

Hi everyone,

I'm just getting started with lilypond, but I do have some programming 
knowledge.

I'm having trouble with this input:

\version "2.15.24"
\include "english.ly"

global = {
        \time 2/4
        \key d \major
        }

bassPart = \relative c' {
        \clef bass
        r4 a16 a a a
        a a a a a a a a 
        }

pianoRight = \relative c'' {
        \acciaccatura gs8 a8 r a,4~
        a r
        }


pianoLeft = \relative c {
        \clef bass
        \acciaccatura gs8 a8 r a,4~
        a r
        }

\score {
        <<
        \new Staff << \global \bassPart >>
    \new PianoStaff <<
        \new Staff << \global \pianoRight >>
                \new Staff << \global \pianoLeft >>
        >>
        >>
        \layout { }
}

Which renders with two sets of clefs with the acciaccaturas in between. I am 
aware that there is documentation about this, but I have not been able to 
understand the problem after hours of trying - clearly it relates to starting 
with the acciaccaturas, but I have not found a solution.

Thanks in advance for your help. I am really looking forward to grasping enough 
of this to convert everything to lilypond.

Cheers,

NL