В чем причина ошибки A field or property with the name 'Key' was not found on the selected data source?

Question

[Klerkli]

Мне нужно сделать группировку по order.OrderID

var query = from order in mydb.Orders
    join customer in mydb.Customers on order.CustomerID equals customer.CustomerID
    join employee in mydb.Employees on order.EmployeeID equals employee.EmployeeID
    join shipper in mydb.Shippers on order.ShipVia equals shipper.ShipperID
   join orderdetail in mydb.Order_Details on order.OrderID equals orderdetail.OrderID
     join product in mydb.Products on orderdetail.ProductID equals product.ProductID
      select new
  {
OrderID = order.OrderID,                                 
CustomerName = customer.CompanyName,                                         
EmployeeName = employee.FirstName,
ShipperName = shipper.CompanyName,                                   
Products = product.ProductName,                                         
TotalPrice = orderdetail.UnitPrice * orderdetail.Quantity           
 }  into d
      group d by d.OrderID;

Затем я хочу вывести данные сюда

<asp:LinqDataSource 
    ContextTypeName="NorthDataContext" 
    TableName="Contacts" 
    Where="EmailPromotion=1"
    ID="Linq" 
    runat="server">
            
</asp:LinqDataSource>
         <asp:GridView ID="Grid" runat="server">
               </asp:GridView>

Вывожу таким образом

Grid.DataSource = query;
                Grid.DataBind();