Thanks fir this swift reply,

The error occured when I tried the following operations 

Emacs -Q
Calendar
i d     ;;  (M-x diary-insert-entry) returns no diary file
C-x f ~/diary   ;; to create diary file and create an appointment :  Mar 
09, 2010 ....
m  ;; (diary-mark-entries)
returns the error 
diary-mark-entries-1: Wrong type argument: stringp, nil


In GNU Emacs 23.1.1 (i386-mingw-nt5.1.2600)
 of 2009-07-30 on SOFT-MJASON
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.4)'

Important settings:
  value of $LC_ALL: fr_FR@euro
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: FRA
  value of $XMODIFIERS: nil
  locale-coding-system: cp1252
  default-enable-multibyte-characters: t

Major mode: Calendar

Minor modes in effect:
  shell-dirtrack-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<down-mouse-1> <mouse-1> <escape> x c a l e n d a r 
<return> s C-x C-f C-g C-x C-f c : / <tab> <backspace> 
<backspace> <backspace> ~ / d i a r <tab> y <return> 
M a r SPC 0 1 , SPC 2 1 0 <left> <left> 0 <right> <right> 
SPC 1 1 : 0 0 - 1 9 : 0 0 SPC T E S T C-x C-s C-x k 
<return> i d n e w s <backspace> <backspace> <backspace> 
<backspace> <up> C-k C-t C-y <left> <C-left> <C-left> 
<C-left> <C-left> <C-left> C-_ C-_ C-y <down> <down> 
<up> <down> C-y <C-backspace> I M P O C-x C-s C-x o 
m <help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<menu-bar> <help-menu> <send-emacs-bug-report>

Recent messages:
Loading tramp...done
(New file)
Saving file c:/Documents and Settings/hibti-moh/Application Data/diary...
Wrote c:/Documents and Settings/hibti-moh/Application Data/diary
Mark set
Undo! [2 times]
Mark set [2 times]
Saving file c:/Documents and Settings/hibti-moh/Application Data/diary...
Wrote c:/Documents and Settings/hibti-moh/Application Data/diary
Marking diary entries...
diary-mark-entries-1: Wrong type argument: stringp, nil



rgm@gnu.org 
22/02/2010 18:56

A
mohamed.hibti@edf.fr
cc
5619@debbugs.gnu.org
Objet
Re: bug#5619: 23.1; Calendar (diary-mark-entries)






Mohamed HIBTI wrote:

> I tried emacs with the option -Q and then setting the diary file.
> The 'diary-mark-entries command leads to an error 
>
> (wrong-type-argument stringp nil)

Please describe *exactly* what you did. Eg:

emacs -Q
M-x calendar
M-x customize-variable
etc etc

Please also try and reduce the diary-file to the minimum needed to
show the problem, and post it here.

And also do

M-x toggle-debug-on-error

and post the backtrace that you get when the error occurs.

Thanks.

> In GNU Emacs 23.1.1 (i386-mingw-nt5.1.2600)