[Orgmode] Trying to write an elisp function to move subtree to end of file

[Charles Cave]

I am writing an elisp function to move the subtree (at the point/cursor)
to the end of the file.  The code from .elisp is shown

I get an error message "Invalid function: (org-cut-subtree)

(defun move-subtree-to-end ()
  (interactive)
  (save-excursion (
  (org-cut-subtree)
  (end-of-buffer)
   (org-paste-subtree))
  )
)
(global-set-key (kbd "C-c e") 'move-subtree-to-end)

To give you background, my todo list/journal has been captured in 
a date tree and I would like to move an item to the end of the buffer.
The reason for this will be explained in an upcoming article!

Refiling is not applicable as (I don't think) the target can be defined.

A date tree looks like:

* 2010
** 2010-07 July...
** 2010-08 August...
** 2010-09 September
*** 2010-09-21 Tuesday
**** Headline of added entry
**** Headline of another entry
*** 2010-09-22 Wednesday


Thanks!
Charles