PieChart display

Hello everybody,

I have a problem in my display with an ajax Piechart.

My code is :

Dim chtPlanif As New PieChart
Dim item As New PieChartValue
With chtPlanif
.ID = "pieChart01"
.ChartHeight = "200"
.ChartWidth = "250"
item.Category = "USA"
item.Data = "20"
chtPlanif.PieChartValues.Add(item)
item = New PieChartValue
item.Category = "China"
item.Data = "80"
chtPlanif.PieChartValues.Add(item)
item = New PieChartValue
item.Category = "UK"
item.Data = "300"
chtPlanif.PieChartValues.Add(item)

End With

and the result is not a correct pie but this:

Can you help me, I don't what is not correct in my code.

Thanks