[mew-int 00715] problem with charset

[Dmitry S. Sivachenko]

Hello!

I use mew-2.1 on Emacs 21.1.  I have one problem.
I have these lines in my .emacs:
(codepage-setup 1251)
(define-coding-system-alias 'windows-1251 'cp1251-dos)

But when I am trying to read e-mail which has charset=windows-1251,
mew prints: 
X-Mew: Charset (windows-1251) for body in not supported.

How can I tune mew to correctly display messages in windows-1251 encoding?

Thank you in advance,
--dima