Telerik 在 Silverlight 中报告，参数未到达服务器

我是这样传递参数的：

        public PrintReport()
    {
        InitializeComponent();
        this.ReportViewer1.RenderBegin += new Telerik.ReportViewer.Silverlight.RenderBeginEventHandler(ReportViewer1_RenderBegin);
    }
    void ReportViewer1_RenderBegin(object sender, Telerik.ReportViewer.Silverlight.RenderBeginEventArgs args)
       {
        args.ParameterValues["ObjectTypeId"] = 40;
        args.ParameterValues["Page"] = 1;
        args.ParameterValues["PageSize"] = 10;
    }

在服务器中，我正在这样做：

    public partial class ObjectInstancesReport : Telerik.Reporting.Report
{
    private IEnumerable<ObjectInstance> _objectInstances;
    public ObjectInstancesReport()
    {
        InitializeComponent();
        var objectTypeId = this.ReportParameters["ObjectTypeId"].Value == null ? 40 : (int)this.ReportParameters["ObjectTypeId"].Value;
        var searchText = (string)this.ReportParameters["SearchText"].Value;
        var page = this.ReportParameters["Page"].Value == null ? 1 : (int)this.ReportParameters["Page"].Value;
        var pageSize = this.ReportParameters["PageSize"].Value == null ? 20 : (int)this.ReportParameters["PageSize"].Value;

但我只得到空值

        public ObjectInstancesReport()
    {
        //
        // Required for telerik Reporting designer support
        //
        InitializeComponent();
        table1.ItemDataBinding += new EventHandler(table1_ItemDataBinding);
        this.DataSource = null;
        this.Report.NeedDataSource += new EventHandler(Report_NeedDataSource);
    }
    void Report_NeedDataSource(object sender, EventArgs e)
    {
        var objectTypeId = this.ReportParameters["ObjectTypeId"].Value == null ? 1 : Convert.ToInt32(this.ReportParameters["ObjectTypeId"].Value);
        var searchText = (string)this.ReportParameters["SearchText"].Value;
        var page = this.ReportParameters["Page"].Value == null ? 1 : Convert.ToInt32(this.ReportParameters["Page"].Value);
        var pageSize = this.ReportParameters["PageSize"].Value == null ? 20 :  Convert.ToInt32(this.ReportParameters["PageSize"].Value);