[h-e-w] Adding to ps-print-hook problems

[Jeff Rancier]

Hi all.  I wanted to create a simple function to prompt me for the n-up
number of pages to print when I run the function,
ps-print-buffer-with-faces.  Here's what I came up with:

(defun jbr-ps-print-n-up-hook (number-of-pages)
  (interactive "nN-up number of pages: ")
  (setq ps-n-up-printing number-of-pages))

(add-hook 'ps-print-hook 'jbr-ps-print-n-up-hook)

I thought that was pretty straight forward.  When I select that from the
menu-bar, I get the following in my *Messages* buffer:

Debugger entered--Lisp error: (wrong-number-of-arguments (lambda
(number-of-pages) (interactive "nN-up number of pages: ") (setq
ps-n-up-printing number-of-pages)) 0)
  jbr-ps-print-n-up-hook()
  run-hooks(ps-print-hook)
  ps-spool-with-faces(1 2947 nil)
  ps-print-with-faces(1 2947 nil)
  ps-print-buffer-with-faces(nil)
* call-interactively(ps-print-buffer-with-faces)

Is that the wrong-number-of-arguments to run-hooks?  And if so, is that a
bug in ps-print?  Or am I incorrectly writing my hook,
jbr-ps-print-n-up-hook?  I am simply calling ps-print-buffer-with-faces()
incorrectly, now that it is interactive?

Jeff