How to expand all the members of a hierarchy in Silverlight OlapChart?

 OlapReport olapReport = new OlapReport();
 olapReport.Name = "Sales Report";
 olapReport.CurrentCubeName = "Adventure Works";
 DimensionElement dimensionElementColumn = new DimensionElement();
 //Specifies the name for the dimension element.
 dimensionElementColumn.Name = "Date";
 //Adds level element along with hierarchy element.
 dimensionElementColumn.AddLevel("Fiscal", "Fiscal Year");
 DimensionElement dimensionElementRow = new DimensionElement();
 //Specifies tge name for the dimension element.
 dimensionElementRow.Name = "Customer";
 //Adds level element along with the hierarchy element.
 dimensionElementRow.AddLevel("Customer Geography", "Country");
 //Adds the DrillState as ExpandAll to expand all members by default.
 dimensionElementRow.DrillState = DrillState.ExpandAll;
  ////Creates measure element.
 MeasureElements measureElement = new MeasureElements();
 measureElement.Elements.Add(new MeasureElement { Name = "Internet Sales  Amount" });
////Adds dimension to the categorical axis.
olapReport.CategoricalElements.Add(new Item { ElementValue = dimensionElementColumn });
////Adds measure to the categorical axis.
olapReport.CategoricalElements.Add(new Item { ElementValue = measureElement });
///Adds dimension element to the series axis.
olapReport.SeriesElements.Add(new Item { ElementValue = dimensionElementRow });

Dim olapReport As New OlapReport()
olapReport.Name = "Sales Report"
olapReport.CurrentCubeName = "Adventure Works"
Dim dimensionElementColumn As New DimensionElement()
'Specifies the name for the dimension element.
dimensionElementColumn.Name = "Date"
'Adds the level element along with the hierarchy element.
dimensionElementColumn.AddLevel("Fiscal", "Fiscal Year")
Dim dimensionElementRow As New DimensionElement()
'Specifies the name for the dimension element.
dimensionElementRow.Name = "Customer"
'Adds the level element along with the hierarchy element.
dimensionElementRow.AddLevel("Customer Geography", "Country")
'Adds the DrillState as ExpandAll to expand all members by default.
dimensionElementRow.DrillState = DrillState.ExpandAll
'Creates measure element.
Dim measureElement As New MeasureElements()
measureElement.Elements.Add(New MeasureElement With {.Name = "Internet Sales Amount"})
'Addsdimension to the categorical axis.
olapReport.CategoricalElements.Add(New Item With {.ElementValue = dimensionElementColumn})
'Adds measure to the categorical axis.
olapReport.CategoricalElements.Add(New Item With {.ElementValue = measureElement})
'Adds dimension to the series axis.
olapReport.SeriesElements.Add(New Item With {.ElementValue = dimensionElementRow})