write file with coding-system utf-16 doesnt work

[Dirk Zabel]

Hi,
if i try to save a file with coding-system utf-16-le, i keep getting the 
message
  symbol's function definition is void: utf16-le-pre-write-conversation
With tuf-16-be, i get the corresponding message:
  symbol's function definition is void: utf16- be-pre-write-conversation

On the other hand utf-8 works fine.

M-x emacs-version gives:
  GNU Emacs 21.3.1 (i386-mingw-windows98.2222) of 2004-03-10 on NYAUMO

As far as i can see, this is the current binary package available for win32.

I would be grateful for any hint.

Thanks in advance
  Dirk