There was a bug when the entry to be edited was invisible.
@@ -1,5 +1,7 @@
2009-02-20 Carsten Dominik <carsten.dominik@gmail.com>
+ * org.el (org-priority): Also find invisible heading.
+
* org-colview-xemacs.el (org-columns-edit-value): No special
treatment for `org-todo' prefix.
@@ -9580,7 +9580,7 @@ ACTION can be `set', `up', `down', or a character."
(setq action (or action 'set))
(let (current new news have remove)
(save-excursion
- (org-back-to-heading)
+ (org-back-to-heading t)
(if (looking-at org-priority-regexp)
(setq current (string-to-char (match-string 2))
have t)