[Orgmode] how to set faces?

[Uwe Brauer]

Hello 

The following setting works in lisp mode

  (let ((lisp-regexp-4 " ?\\(\\<\\*[a-zA-Z]*\\*\\>\\)"))
    (setq lisp-font-lock-keywords-1
          (append lisp-font-lock-keywords-1
                  (list (list lisp-regexp-4 0
                              'font-lock-log-warn-face t)))) 
    (setq lisp-font-lock-keywords-2
          (append lisp-font-lock-keywords-2
                  (list (list lisp-regexp-4 0
                              'font-lock-log-warn-face t)))))

Every word surrounded by an * gets highlighted by the
font-lock-log-warn-face. 

I tried something similar for org-mode, like 

  (let ((lisp-regexp-4 " ?\\(\\<\\*[a-zA-Z]*\\*\\>\\)"))
    (setq org-font-lock-keywords
          (append lisp-font-lock-keywords-1
                  (list (list lisp-regexp-4 0
                              'font-lock-comment-warn-face t)))))


Or 

(add-to-list 'org-font-lock-keywords            
'(" ?\\(\\<\\*[a-zA-Z]*\\*\\>\\)" 1 'font-lock-comment-warn-face append t))

But it does not work, 

Can somebody give me a hint please?

Uwe Brauer