collapsible content

I'm a newbie trying to make a very simple collapsible content script. It doesn't work. Could someone please, please help?

<script type="text/javascript"><!--

function toggle(sec){
    if(document.getElementById(sec).style.visibility == 'hidden'){
        document.getElementById(sec).style.visibility = 'visible'
        } else {if(document.getElementById(sec).style.visibility == 'visible'){
        document.getElementById(sec).style.visibility = 'hidden'
        }
    }
}
//--></script>

<div onClick='javascript:toggle('change')'>Click to change</div>

<div id='change' style='visibility:hidden'>ta da!</div>

Thanks in advance.