calendar-date-style

[Pingouin]

Hello,

I recently upgraded to Emacs-23.1.1.  I have an issue with calendar-
date-style.  In calendar I always used "european" date style, all my
appointments and meetings are set up with this style; I had the line
(setq european-calendar-style t) in my .emacs, that did the trick but
now Emacs-23 complains telling me this is an obsolete variable; it
tells me to use "calendar-date-style" instead, but the doc says:

|______________
Setting this variable directly does not take effect (if the
calendar package is already loaded).  Rather, use either
M-x customize or the function `calendar-set-date-style'.
|______________

In .emacs I tried to use the function "calendar-set-date-style" every
way I could think of but with no luck!  Please an example!

I also tried to set "calendar-date-style" through M-x customize, as
suggested.  After setting it to "european", clicking the "Save for
future sessions" button yielded the following error:

|--------------------------------
Debugger entered--Lisp error: (void-function recentf-expand-file-name)
  recentf-expand-file-name("c:/EMACS/.emacs")
  custom-save-all()
  Custom-save((push-button :tag "Save for future sessions" :help-echo
"Apply all settings in this buffer and save them for future Emacs
sessions." :action Custom-save :button-overlay #<overlay from 322 to
346 in *Customize Option: Calendar Date Style*> :from #<marker (moves
after insertion) at 322 in *Customize Option: Calendar Date
Style*> :to #<marker at 346 in *Customize Option: Calendar Date
Style*>) (mouse-1 (#<window 3 on *Customize Option: Calendar Date
Style*> 333 (374 . 40) 251207367 nil 333 (36 . 2) nil (8 . 4) (10 .
22))))
  widget-apply((push-button :tag "Save for future sessions" :help-echo
"Apply all settings in this buffer and save them for future Emacs
sessions." :action Custom-save :button-overlay #<overlay from 322 to
346 in *Customize Option: Calendar Date Style*> :from #<marker (moves
after insertion) at 322 in *Customize Option: Calendar Date
Style*> :to #<marker at 346 in *Customize Option: Calendar Date
Style*>) :action (mouse-1 (#<window 3 on *Customize Option: Calendar
Date Style*> 333 (374 . 40) 251207367 nil 333 (36 . 2) nil (8 . 4)
(10 . 22))))
  widget-apply-action((push-button :tag "Save for future
sessions" :help-echo "Apply all settings in this buffer and save them
for future Emacs sessions." :action Custom-save :button-overlay
#<overlay from 322 to 346 in *Customize Option: Calendar Date
Style*> :from #<marker (moves after insertion) at 322 in *Customize
Option: Calendar Date Style*> :to #<marker at 346 in *Customize
Option: Calendar Date Style*>) (mouse-1 (#<window 3 on *Customize
Option: Calendar Date Style*> 333 (374 . 40) 251207367 nil 333 (36 .
2) nil (8 . 4) (10 . 22))))
  byte-code("      \"rʎ \n : 
|_____________________

Any suggestions, thanks,

Gérald