Dynamically Changing A DIV

I have a few radio boxes where a user can choose different options and
I want to show an explanation of each option after it's clicked.
Here's what I have:

<script type="text/JavaScript">

function toggle(o){
o.className = ( o.className == "show" ) ? "hide" : "show";
}

'function describetype(){
' if (window.event.srcElement.value == "starter")
typedesc.innerHTML="A Starter request is for a new employee who's
never worked for cadbury or the Bottling Group before.";
' if (window.event.srcElement.value == "leaver")
typedesc.innerHTML="A Leaver request is for an existing employee who's
permanently leaving the company.";
'}

'function starter(){
'typedesc.innerHTML="A Starter request is for a new employee who's
never worked for cadbury or the Bottling Group before.";
'}

'function leaver(){
'typedesc.innerHTML="A Leaver request is for an existing employee
who's permanently leaving the company.";
'}

function describetype(o){
if (o == "starter"){
typedesc.innerHTML="Starters are...etc.";
}
if (o == "leaver"){
typedesc.innerHTML="Leavers are...etc.";
}
}

</script>

The first "toggle" function works fine but the "describetype" won't
work. Here's the HTML:

....
<td class="layout bold">
<input type="radio" name="reqtype" value="starter"
checked="checked" onclick="describetype(starter)"Starter<br>
<input type="radio" name="reqtype" value="leaver"
onclick="describetype(leaver)"Leaver<br />
</td>
<td class="layout bold">
<input type="radio" name="reqtype" value="mover"Mover<br />
<input type="radio" name="reqtype" value="adhoc"Ad Hoc
</td>
....

The error keeps saying that "starter" or "leaver" is undefined. I'm
not much of a javascript guy (mostly the cut and paste variety myself)
but everything I've seen says this should work. No?