Binding keymap with emacspeak

[Edhoari Setiyoso <edhoari.s@xxxxxxxxxxx>]

Hi list,

I',m new with emacs/emacspeak, therefore I may ask lots of basic
questions here. Please bare with me.

I tried to map a command with
additional auditory icon. Therefore I use following command

(global-set-key (kbd "C-x C-;")   
		(lambda ()
		  (emacspeak-auditory-icon 'modified-object)
		  (comment-line 1)))

Unfortunately it doesn't work with error message:
Wrong type argument: commandp, (lambda nil (emacspeak-auditory-icon (quote modified-object)) (comment-line 1)) 

If i don't use lambda function and separate it in different function
then it's works. I wonder why?

Best Regards

-- 
Edhoari Setiyoso