How to validate the cellset using a server-side event?

protected void Page_Load(object sender, EventArgs e)
{
(this.OlapClient1.OlapDataManager as OlapDataManager).CellSetChanged += OlapClient_CellSetChanged;
}
void OlapClient_CellSetChanged(object sender, CellSetChangedEventArgs e)
{
    if (e.NewCellSet == null)
    { 
    }
}

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
AddHandler (TryCast(Me.OlapClient1.OlapDataManager, OlapDataManager)).CellSetChanged, AddressOf OlapClient_CellSetChanged
End Sub
Private Sub OlapClient_CellSetChanged(ByVal sender As Object, ByVal e As CellSetChangedEventArgs)
 If e.NewCellSet Is Nothing Then
 End If
End Sub