FusionCharts allows you to set event listeners in charts (swf/js) built since v3.2. So, please check if you are using charts having version 3.2 or above.
Moreover, please also check if you have FusionCharts.js which is of v3.2 or above.
More pointers on adding event listeners:
Make sure to use the appropriate variable name/js reference of the chart.
var myChart = new FusionCharts(...);
myChart.addEventListener ("DrawComplete" , myChartListener );
Basic Documentation : http://www.fusioncharts.com/docs/?JavaScript/JS_EventOverview.html#advanced
API Reference : http://www.fusioncharts.com/docs/?JavaScript/API/Events.html
You can also use other chart reference models like:
FusionCharts("myChartId").addEventListener("DrawComplete" , myChartListener);
getChartFromId( DOMId ).addEventListener("DrawComplete" , myChartListener);
FusionCharts.items["myChartId"].addEventListener("DrawComplete" , myChartListener);
You can also check out samples from :
http://www.fusioncharts.com/code/JavaScript/Basics/ListeningToEvents/Using_JavaScript_advanced_event_registration_model.html
Menu containing other examples of FusionCharts JavaScript API : http://www.fusioncharts.com/code/JavaScript/index.html