markup-system-spacing syntax help

[Richard Shann]

I can't seem to get the vertical spacing settings 

http://www.lilypond.org/doc/v2.19/Documentation/notation/flexible-vertical-spacing-paper-variables

to do anything:

\version "2.19.25"
\header {
title = "title"
}
\paper {
markup-system-spacing = 20
}

\score {
\repeat unfold 200 { c''1*4/4 } 
} 


No matter what value I use, the distance between "title" and the first
system is unchanged.
Any ideas?

Richard