message-reply-headers and posting styles

[Dmitry Bely <dbely@mail.ru>]

Having read the Gnus manual, specifically

[---cut---]
Posting Styles
==============
...
The attribute value can be a string (used verbatim), a function with
zero arguments (the return value will be used), a variable (its value
will be used) or a list (it will be `eval'ed and the return value will
be used).  The functions and sexps are called/`eval'ed in the message
buffer that is being set up.  The headers of the current article are
available through the `message-reply-headers' variable, which is a
vector of the following headers: number subject from date id references
chars lines xref extra.
[---cut---]

I wrote the following:

(setq gnus-posting-styles
      '(("fido7"
	 ("X-Comment-To"
	  (lambda ()
	    (let ((from (aref message-reply-headers 2)))
	      (if (string-match " *<.*> *" from)
		  (concat (substring from 0 (match-beginning 0)) (substring from (match-end 0)))
		(if (string-match "\(.*\)" from)
		    (substring from (+ (match-beginning 0) 1) (- (match-end 0) 1))
		  from)))))
	 )))

But this does not work. message-reply-headers variable is nil inside
lambda. Could you explain me what am I doing wrong?

Hope to hear from you soon,
Dmitry