problems with afterGrace

[Till Rettig]

Hello all,

I just tried to apply the example from the docs for 2.11, chapter 6.5.7 
for changing the distance from afterGrace notes.
But I get always  a warning that the right context cannot be found. 
Would it be good to add a better example to the docs?

this is my minimal example:

\version "2.11.23"
\relative c'' { c1 {

\set afterGraceFraction = #(cons 2 4)

\afterGrace d1 { c16[ d] } c4} }

\layout {
   ragged-right = ##t
   }

Greetings
Till