Jquery show div when link gets clicked

Im trying to show/hide a div using jquery when a link gets clicked. I put this in my head section:

<script type="text/javascript"> 
  $("#attach_box").click(function {
    $("#sec_box").show()
    });        
</script>

I have a link that looks like this:

<a href="#" id="attach_box">+ Add a Postal Address (If Different)</a>

And a div that looks like this:

<div id="sec_box" style="display: none;">
Hello world!!               
</div>

This doesn't work and I can't figure out why. Any ideas?