Javascript problem

[ZomgStuff]

So this is really ticking me off as I've been starring at this for an hour and can't figure out why nothing happens when I click.

In the headinclude template I have

<script type="text/javascript" src="clientscript/david.js"></script>

<div id="survey123" class="survey_box"><a href="#" onclick="openSurveyBox('survey123');">lulz</a></div>

And in david.js I have

PHP Code:

function openSurveyBox( $displayobject)
{
    barz = fetch_object( $displayobject );
    barz.innerHTML = "lolozzf";
} 


My css definition is

.survey_box {
background:#FFFFDD none repeat scroll 0% 50%;
border:1px solid #777777;
color:#555555;
cursor:pointer;
display:block;
height:500px;
left:350px;
opacity:1;
position:absolute;
top:50px;
width:500px;
z-index:5;
}

Why won't it change when I click?