condense multi-measure repeats in drum part?

[Matthew Rowles]

Hi all

When engraving this part, the multi-measure rests are written out in full, rather than as groups of multi-measure rests

\version "2.18.2"
\score{
   \new DrumStaff <<
      \override MultiMeasureRest.expand-limit = #2
      \drummode {
         R1*4
         R1*8
         R1*10
         R1*4
         cab4 cab cab r
      }
   >>

}

What am I doing wrong and how can I get the multi-measure rests?

Matthew