problems with save-excursion

[filcab]

I have the following function:
(defun copy-line ()
   (interactive)
   (save-excursion
      (beginning-of-line)
      (set-mark-command)
      (end-of-line)
      (copy-region-as-kill)))

But it's not working...
It says:
save-excursion: Wrong number of arguments: #[(arg) ... (some trash)


Any clues?