setArea and callback on Bar chart in IE

I am attempting to implement a bar chart with clickable bar areas to create a drill-down effect. I was able to get it to work using the setArea(unit, callback) method...however, it does not work in IE (surprise, surprise). It works perfectly in Firefox, and works in Chrome and Safari. I'm not getting any error messages in IE...just nothing happens when I click the bar. Here's a code sample of what I'm doing:

var myData = new Array(['Friend 1', 8], ['Friend 2', 5], ['Friend 3', 20]);
var myChart = new JSChart('chartcontainer', 'bar');
myChart.setDataArray(myData);
myChart.setArea('Friend 1', function() {
    goToUnit(8);
});

function goToUnit(unit) {
    alert(unit);
}

Any ideas on why that wouldn't work in IE? Thanks!