(setq dired-guess-shell-alist-user
      '(("\\.[cC]hm$" "kchmviewer")
        ("\\.pdf$" (concat "C:\\Program" " Files\\Adobe\\Acrobat" " 4.0\\Reader\\AcroRd32.exe")))))


when I put ! on the selected pdf, got error in the minibuffer that is : c:\program is not a valid path, any idea ?

I am on emacs for win32