WPF:Chart未绘制图表

我正在WPF应用程序中开发一个图表。但它并没有显示图表。图表绘图区域是空白的，而我可以根据代码中的值List的数量看到图例的数量。

XAML

<chartingToolkit:Chart HorizontalAlignment="Stretch"
                       x:Name="MyPie"
                       Margin="10"
                       Title="Total Voting Percentage"
                       VerticalAlignment="Stretch">
    <chartingToolkit:PieSeries ItemsSource="{Binding}"
                               DependentValuePath="Total Participants"
                               IndependentValuePath="Total Voted" />
</chartingToolkit:Chart>    

代码隐藏

public partial class TotalVoting : Window
{
    int TotalParticipant;
    int TotalVoted;
    public TotalVoting()
    {
        InitializeComponent();
        TotalParticipant = int.Parse(da[0].ToString()); //data reaches here
        TotalVoted = int.Parse(da1[0].ToString()) / 2; //data reaches here
        ObservableCollection<Writer> Team = new ObservableCollection<Writer> 
        { 
             new Writer("Total Participants", TotalParticipant), 
             new Writer("Participants Voted", TotalVoted),
             new Writer("Total Participants", TotalParticipant), 
             new Writer("Participants Voted", TotalVoted)
        };
        MyPie.DataContext = Team;
    }
}
public class Writer
{
    public Writer() { }
    public Writer(string writerName, int numOfTypes)
    {
        Name = writerName;
        Types = numOfTypes;
    }
    public string Name { get; set; }
    public int Types { get; set; }
}

当我运行代码时，我可以看到图例的数量，数字为1,2,3。。。因此，对于当前代码，它显示从1到4。但在我的图表控件上没有显示任何图表。任何能让我完成的线索。

---

编辑：代码已更改。。但的结果仍然相同

public void GenerateChart()
{
  List<KeyValuePair<string, double>> valueList = new List<KeyValuePair<string, double>>();
  valueList.Add(new KeyValuePair<string, double>("Apple", 101));
  valueList.Add(new KeyValuePair<string, double>("Banana", 201));
  valueList.Add(new KeyValuePair<string, double>("Cake", 20));
  valueList.Add(new KeyValuePair<string, double>("Others", 200));
  pieChart.Title = "Top Products";
  pieChart.DataContext = valueList;
}

加上时间数CCD_ 1。我可以在图表上显示相同数量的图例，但没有图表：（

希望有人能帮我！！！