Print error from delivered application

Hello all,
I'm trying to create a printed report from my windows delivered 
application, but it won't work.
I must be missing something obvious.

Here is an example test application showing my problem:

print-test.lisp:
(in-package :user)

(defun kill-a-tree ()
  (capi:with-print-job (port)
    (gp:draw-string port "Killing a tree" 20 20)))

This prints some (very small) text when called from lispworks listener.

Here is the delivery script:

delivery.lisp:
(in-package :user)
(load-all-patches)
(compile-file "print-test")
(load "print-test")
(deliver 'user::kill-a-tree "print-test" 0
         :interface :capi)

Here is what I get when running the application :

Error: #<Unbound Marker> fell through ETYPECASE expression.
Wanted one of (WIN32:LOGICAL-FONT SYMBOL).
  1 (abort) Quit process.

Type :b for backtrace, :c <option number> to proceed,  or :? for other 
options

CL-USER 1 : 1 > :b

Call to WIN32::STOCK-FONT-PROTOTYPE
Call to WIN32:DEVICE-STOCK-FONT
Call to WIN32::INIT-DEVICE-MEMORY-DC
Call to (METHOD CAPI-LIBRARY::OPEN-PRINTER (CAPI-WIN32-LIB::R-PRINTER T))
Call to KILL-A-TREE
Call to DELIVERY::MAYBE-RYB-TOP-LEVEL
Call to (SUBFUNCTION MP::PROCESS-SG-FUNCTION MP::INITIALIZE-PROCESS-STACK)


Thanks in advance for any pointers you guys could provide to me as how 
to correct this problem.
My configurations is :
Windows XP SP2
Lispworks 5.1
Printer : HP 950c (though i can't imagine how this would affect the end 
result)


Sacha De Vos