I'm having difficulty with objects.

I'm using dojo chart to create a chart.

If I assign the chart directly. completes successfully.

Code:
var chartObject = {};

createchart();
addGraphXaxis(chartObject )
;
function createchart(){
  chartObject = new Chart("cns_chartNode1");
}

function addGraphXaxis(iChart){
  try{iChart.addSeries('Customer Port', data);}catch(err){}
}
If I change the create function to return the chart. Then I get a TypeError: iChart is undefined in the addGraphXaxis function.

Code:
chartObject = createchart("cns_chartNode1")

function createchart(iNodeName){
  wChart = new Chart(iNodeName);
  return wChart;
}
Any ideas as to what is going on? I'm fairly new to javascript.