invisible barlines

[Stefan Thomas]

Dear Lilypond-users,
I have a problem with the barlines with the below quoted music.
Why are the so short?
What can I do to have it longer?
Thanks for Your support,
Stefan

schlagzwo =
\relative c' { \override Staff.StaffSymbol #'line-count = 1
\clef percussion
r16
c\mf c16-> [ c c32 c] r16
R1
r4 r8 c8~\ppp \startTrillSpan           %schlagzwo 3
c2.~ c16~ c8~\< c16\mp \stopTrillSpan   %schlagzwo 4
r4 r8 c~\ppp\startTrillSpan                      %schlagzwo 5
c8~\<                                               %schlagzwo 6
c16\f \stopTrillSpan r16 r8 r4 r2                    %schlagzwo 7
R1*12


}

\new Staff = "Schlagzeug 2"
                        << \set Staff.instrumentName = "Perc. 2"
                        \set Staff.shortInstrumentName = "Perc. 2"
                        \schlagzwo >>
Stefan Thomas
Siebengebirgsallee 9
50939 Köln
Tel.Fax:0049(0)221/412529
mail: address@hidden