preview-latex and reftex not active!?

[Fabian.Braennstroem@t-online.de (Fabian Brännström)]

Hello,

right now I have three different distributions running. debian stable,
debian testing and gentoo.
I installed emacs, auctex, reftex and preview-latex on each system.

stable: emacs 21.2-1, auctex 11.06-1, preview-latex 0.6.1-1
testing: emacs 21.2-1 auctex 11.13, preview-latex 0.7.8 and
preview-latex-style 0.7.8
gentoo: emacs 21.3, auctex 11.13  , preview-latex 0.7.8 

I'm using for all systems the same .emacs-file, but just for the debian
testing system reftex and preview-latex is activated in the menu when
opening a tex-file.

Does anyone have an idea how to solve that problem?

Thanks!
Greetings
Fabian


_______________________
P.S. My .emacs:
_______________________

(custom-set-variables
  ;; custom-set-variables was added by Custom -- don't edit or cut/paste
it!
  ;; Your init file should contain only one such instance.
 '(case-fold-search t)
 '(current-language-environment "English")
 '(global-font-lock-mode t nil (font-lock))
 '(gnuserv-program (concat exec-directory "/gnuserv"))
 '(load-home-init-file t t)
 '(transient-mark-mode t)
 '(uniquify-buffer-name-style (quote forward) nil (uniquify)))
 '(auto-save-timeout 1)

 (custom-set-faces
  ;; custom-set-faces was added by Custom -- don't edit or cut/paste it!
  ;; Your init file should contain only one such instance.
 )

(require 'tex-site)

 (setq outline-minor-mode t)
 (setq latex-mode)
 (setq latex-math-mode)


(add-hook 'LaTeX-mode-hook 'turn-on-reftex) 
(setq reftex-plug-into-AUCTeX t)


 ;; ===================================================================
 ;; Preview LaTeX
 ;; ===================================================================
(cond ((file-readable-p
"/usr/share/emacs/site-lisp/preview-latex/preview.el")
        (if (and window-system (x-display-color-p))
          (progn 
            (require 'preview)))))
 ;; ===================================================================
 ;; Preview LaTeX End
 ;; ===================================================================
;(load "/usr/share/emacs/site-lisp/preview-latex/preview-latex.el" nil t
t)
(add-hook 'LaTeX-mode-hook 'LaTeX-preview-setup)
(autoload 'LaTeX-preview-setup "preview")
(add-to-list 'load-path "/usr/share/emacs/site-lisp/preview-latex/")