Problem printing rich-text-pane

When I try to print a rich-text-pane with LW 5.1 and XP, I get the error:

No applicable methods for #<STANDARD-GENERIC-FUNCTION
CAPI-LIBRARY::REPRESENTATION-PRINT-RICH-TEXT-PANE
20BF134A> with args (#<Representation
WIN32:R-TOP-LEVEL-INTERFACE #<TEST-RT-INTERFACE "Print
test" 200B05DB>> #<CAPI::PRINTER "HP LaserJet 1200 Series PCL"
20088C1F> :JOBNAME NIL :SELECTION NIL)

If I save the file, it prints fine from XP.

Below is the example code. Thanks for any help.

Mitch

(capi:define-interface test-rt-interface ()
   ()
   (:panes
    (display-window
     capi:rich-text-pane
     :accessor display-window
     :text "Test text"))
   (:menus
    (file-menu
     "File"
      (("Print"
       :callback-type :interface
       :callback 'print-pane))))
    (:layouts
     (main-layout
      capi:column-layout
      '(display-window)))
    (:menu-bar file-menu)
    (:default-initargs
     :layout 'main-layout
     :title "Print test"
     :best-height 100
     :best-width 100))

(defun print-pane (pane)
   (capi:print-rich-text-pane pane))