C# 以对象作为数据源的RDLC

我正试图显示来自我的类对象的rdlc报告

这是上课时间

public class BillInfo
{
    public String Name { get; set; }
    public String Date { get; set; }
    public String splInstructions { get; set; }
    public List<OrderItem> oItems { get; set; }
    public String GrossTotal { get; set; }
    public String DiscountAmount { get; set; }
    public String NetTotal { get; set; }
}

public class OrderItem
{
    public OrderItem() { }
    public OrderItem(String sNo, String Qty, String Amt, String ttl) 
    {
        this.SNo = sNo;
        this.Quantity = Qty;
        this.Amount = Amt;
        this.Total = ttl;
    }

    public String SNo { get; set; }
    public String Quantity { get; set; }
    public String Amount { get; set; }
    public String Total { get; set; }
}

我添加数据源的第二行给出了这个错误

Value does not fall within the expected range.

在Microsoft.Reporting.WinForms.ReportDataSource.set_ValueObject value\r\n的Billinator.ReportViewer.ReportViewer_LoadObject sender中，C:\Users\Guest1\Desktop\Billinator\Billinator\ReportViewer.cs中的EventArgs e:System.Windows.Forms.Form.OnLoadEventArgs e\r\n位于System.Windows.Forms.Control.CreateControlBoolean Fignorevible\r\n位于System.Windows.Forms.Control.CreateControl\r\n位于System.Windows.Forms.Control.WmShowWindowMessage&m\r\n位于System.Windows.Forms.Control.WndProcMessage&m\r\n位于System.Windows.Forms.Control.ControlNativeWindow.WndProcMessage&m\r\n位于System.Windows.Forms.NativeWindow.DebuggableCallbackIntPtr hWnd，Int32 msg，IntPtr wparam，IntPtr lparam

请指出哪里出了问题

MainForm.GetBillData返回的是什么类型？你能发布那个方法的代码吗？

Value does not fall within the expected range.