Trouble Understanding VerticalAxisGroup - advice needed please

[James Lowe]

Hello,

I've been trying to fathom how to reduce the between space two grouped
staffs. I'm obviously not understanding the Notation Reference as I have
tried a variety of places where I have pasted what I think is the correct
settings but nothing seems to change the defaults.

My construction is as follows.

-----

\version "2.13.40"

\musicA = { a b c d etc.}
\musicB = { a b c d etc.}
\musicC = { a b c d etc.}

\score {
  <<
    \new RhythmicStaff {
      <<
      \new Voice {
        \musicA
      }
      \new Voice {
        \MusicB
      }
     >>
    }
    \new RhythmicStaff {
      \MusicC
     }
  >>
  \layout { }
}


-----

This all engraves fine. But I have a lot of white space between the two
RhythmicStaffs that are grouped together that I'd like to reduce.

I tried to insert (using silly numbers to see if it was just my values
being too conservative or not)

\override VerticalAxisGroup #'staff-staff-spacing =
  #'((basic-distance . 4)
     (minimum-distance . 4)
     (padding . -10))


In a variety of places. If for example I followed the NR's example and put
something like 


\score {
  <<
    \new RhythmicStaff \with {
      \override VerticalAxisGroup #'staff-staff-spacing =
        #'((basic-distance . 4)
           (minimum-distance . 4)
           (padding . -10))
...


Etc.

I get a compilation error with an unexpected '}' if I remove the '\with',
but leave the braces 'as is' the compilation error goes away but still
nothing changes.

If I put this \override in the \layout { } it compiles but nothing changes.

I also tried default-staff-staff-spacing but again nothing happens.

:(

Can someone point me in the right direction? Is my version 2.13.40 too
old? Or does this not work with RhythmicStaff and so on.

Thanks for any pointers.

James