问如何使用Linq ToDictionary返回字典项中包含多个值的字典？

EN

Public Class order
    Public ID As Integer
    Public Name As String
    Public DateStamp As Date
End Class
Public Function GetOrdersSortedByDate() As Generic.Dictionary(Of String, Generic.List(Of User))
    Dim orders As New List(Of order)(New order() _
    {New order With _
     {.ID = 1, .Name = "Marble", .DateStamp = New Date(2010, 1, 1)}, _
     New order With _
     {.ID = 2, .Name = "Marble", .DateStamp = New Date(2010, 5, 1)}, _
     New order With _
     {.ID = 3, .Name = "Glass", .DateStamp = New Date(2010, 1, 1)}, _
     New order With _
     {.ID = 4, .Name = "Granite", .DateStamp = New Date(2010, 1, 1)}})

    ' Create a Dictionary that contains Package values, 
    ' using TrackingNumber as the key.
    Dim dict As Dictionary(Of String, List(Of order)) = _
        orders.ToDictionary(Of String, List(Of order))(Function(mykey) mykey.Name, AddressOf ConvertOrderToArray) ' Error on this line

    Return dict
End Function
Public Function ConvertOrderToArray(ByVal myVal As order, ByVal myList As Generic.List(Of order)) As Generic.List(Of order)
    If myList Is Nothing Then myList = New Generic.List(Of order)
    myList.Add(myVal)
    Return myList
End Function

'Public Function ConvertOrderToArray(myVal As order, myList As System.Collections.Generic.List(Of order)) As System.Collections.Generic.List(Of order)'
does not have a signature compatible with delegate 
'Delegate Function Func(Of order, System.Collections.Generic.List(Of order))(arg As order) As System.Collections.Generic.List(Of order)'.