Data is not binding to RadBarChart in silverlight

Question

I am creating RadBarChart in silverlight.

If I hardcode the Yvalue and XCategory values in the same class then the chart shows correct data.

Below is the method I am calling after Initializecomponent() method in Sample.cs class.

public void FillSampleChartData()
    {
        DataSeries dataSeries = new DataSeries();
        dataSeries.Definition = new BarSeriesDefinition();

        dataSeries.Add(new DataPoint() { YValue = 1127.13, XCategory = "Victor" });
        dataSeries.Add(new DataPoint() { YValue = 1123.80, XCategory = "Kishore" });
        dataSeries.Add(new DataPoint() { YValue = 9948.94, XCategory = "Vincent" });

        RadChartSales.DefaultView.ChartArea.DataSeries.Add(dataSeries);
   }

I have doubt if I call same method from other class...barchart not showing any data. Let me know why chart is not displaying data.

//This is my original method

public void FillSampleChartData(IList collection)
 {                              
        int listcount = collection.Count;
        int count = -1;

        double[] myArray1 = new double[listcount];
        string[] myArray2 = new string[listcount];

        foreach (BizFramework.Web.Model.SalesBySalesPersonSummary_Result dtvws in collection)
        {
            count++;
            myArray1[count] = Convert.ToDouble(dtvws.Amount);
            myArray2[count] = dtvws.Salesperson;

        }
        DataSeries dataSeries = new DataSeries();
        dataSeries.Definition = new BarSeriesDefinition();

    if (myArray1.Count() > 0)
        {
            for (int i = 0; i < myArray1.Count(); i++)
            {

             dataSeries.Add(new DataPoint() { YValue = myArray1[i], XCategory = myArray2[i] });
            }

            RadChartSales.DefaultView.ChartArea.DataSeries.Add(dataSeries);
        }
    }