Re: 12/8 problems

[Jon]

I'm really starting to wrap my brain around the idea
of using this software over other notation software,
but I am having a problem. Here is a basic template below:

\version "2.10.33"
\header {
}
\include "english.ly"
staffTrombone = \new Staff  {
\time 4/4
\set Staff.timeSignatureFraction = #'(12 . 8)
\set Staff.instrument="Trombone"
\set Staff.midiInstrument="trombone"
\key d \major
\clef bass
\relative c' {
%bar 1
d4. d4. d4. d4.
}
}

When I run the script and the music gets parsed,
the dotted quarter notes are in groups of three
instead of four, like it is 9/8 instead of 12/8.
Any way to get this properly notated?
Thanks a bunch for the help.

Jon