R help - May 2010 - problem with geepack::geese() argument "soffset"

I get an error message when trying to specify a scale offset using
geese() in library(geepack). Here is a dummy example:

v <- rep( 1:2, each = 100 )
x <- rnorm( 200 ) * sqrt( v )
i <- 1:200
summary( geese( x~1, id=i ) ) # works ok
summary( geese( x~1, id=i, soffset=v ) ) # fails

Error in geese.fit(x, y, id, offset, soffset, w, waves, zsca, zcor, corp,  :
  mean.link invalid.