snowfall and calling C++ code with .C

Dear R-sig-hpc,

I am having trouble using sfSapply on a function that calls a C function
through the .C interface.  When executing in serial I have no errors, but in
parallel I have the error that each node cannot find the function called by
.C

i.e. if I have

myfn <- function(){  .C("myfunction") }

I get the error
C symbol name "myfunction" not in load table



I use sfExportAll() and sfLibrary(mylibrary) before calling the parallel
code.  Thanks so much for your help!

Sincerely,
Carl