Tremolos not working in cued voice

[Gez]

When inserting a cue which contains a tremolo, the note heads and stems 
are showing up but not the beams.  Is it something I've done or missed 
out?  I've made a (reasonably) tiny example:
________________
\version "2.16.2"

cueVoice =

\relative c'' {

R2.

\repeat tremolo 3 { b8 e }

}

mainVoice =

\relative c'' {

\time 3/4

\repeat tremolo 3 { b8 e }

\new CueVoice {\set instrumentCueName = "cue"}

\cueDuring "cue"#UP

{R2. }

\addQuote "cue"{ \cueVoice }

}

\score {

\new Staff \mainVoice

\layout { }

}
___________________


Gez