Accordion doesn't work

Accordion doesn't work

Allò!

I'm just desperated because I'm trying to implement the "easy" accordion widget on my web but It doesn't work.
I've read a lot of about it and I can not understand why it doesn't work because the implementation it's very, very easy!

I'm new at Jquery so I'm sorry if my mistake it's very fool.

I attach my files so I'd appreciate any help.

The problem is that the accordion is expanded even though I wrote 

$(document).ready(function($) {
 
       $('#accordion div').hide();
       $('#accordion h3 a').click(function(){
               $('#accordion h3').slideUp();
               $(this).parent().next().slideDown();
               return false;
       });
});

Thank you ver y much in advanced.