Autoload a major mode

[Bänninger, Dominik]

Hello

I want to creat an own major mode for *.m -files. Therefore I included the
following lines in my .emacs:

(autoload 'matlab-mode "m-mode")
(setq auto-mode-alist (cons '("\.m$" . matlab-mode) auto-mode-alist))

I put the file m-mode.el in the directory  .../emacs/site-lisp. When I open
emacs with a m-file, he will return the error message:

File mode specification error: (error "Autoloading failed to define function 
matlab-mode")

Can anyone tell me, what I did wrong?

Thanks in advance for your help 
Dominik