Problem starting ESS for S-Plus 6 on Windows XP

[Ted Hu]

When I type M-x S
got a debug window,  message

no such file or directory, sh


Emacs  : GNU Emacs 21.2.1 (i386-msvc-nt5.1.2600)
of 2002-03-19 on buffy
Package: ess-mode 5.1.24

I suppose this is the shell variable.  How should I set it?

Thanks,

Ted