Change Staff problem with rests

[Brett Duncan]

Hi

When I used the \change Staff command in a piano arrangement I'm working 
on, I found it necessary to force the stem directions to avoid column 
clashes. No problem. However, I've found that if both parts have a rest 
at the same moment, I get error messages like this...

warning: can't resolve rest collision: rest direction not set

...and a single rest appears rather than two rests (one above the other).

The following snippet shows the problem:

---------------------------------------
staffPiano = \new PianoStaff {
                \time 4/4
                                <<
                \context Staff = "RH" {
                        \clef treble
                        \relative c' {
                                c'1
                                \stemUp
                                b4 g r4 b
                        }
                }
                \context Staff = "LH" {                       
                        \clef bass
                        \relative c {
                                c'1
                                \change Staff = "RH"
                                \stemDown
                                b4 g r4 b
                        }
                }
        >>
}
---------------------------------------

Brett