EF 6从新环境中返回陈旧信息？

Question

Class RBI.Lead：

Public Class Lead
#Region "Constructors "
Public Sub New()
    _cxt = New RDB.RDBContainer
    _person = New RDB.Lead
End Sub

Public Sub New(ID As Guid)
    If Not IsNothing(ID) Then
        If IsNothing(_cxt) Then _cxt = New RDB.RDBContainer
        If IsNothing(_person) Then
            _person = _cxt.Leads.Find(ID)
        End If
    End If
End Sub
#End Region
...
 Public ReadOnly Property Notes As IEnumerable(Of RBI.PersonNote)
    Get
        If Not IsNothing(_person.LeadNotes) Then
            Dim _tmp As IEnumerable(Of RiseBI.LeadNote) = _person.PersonNote.Select(Function(p) New RBI.PersonNote(p, _cxt))
            Return _tmp.ToList
        Else
            Return Nothing
        End If
    End Get
End Property
...
End Class

RDB.Lead：

Partial Public Class Lead
    Public Property Id As System.Guid
    ...        
    Public Overridable Property LeadNotes As ICollection(Of LeadNote) = New HashSet(Of LeadNote)
End Class

向潜在客户添加新备注：

 Public Shared Function AddNote(ID As Guid, Note As String) As Guid
    Dim _cxt As New RDB.RDBContainer
    Dim _tmp As New RDB.PersonNote
    Dim _person = DB.Leads.Find(ID)
    _tmp .Id = Guid.NewGuid()
    _tmp .Note = Note
    _lead.LeadNotes.Add(tmp)
    DB.SaveChanges()
    Return _tmp.ID
End Function

UI方面的事情： 添加新笔记：

 Protected Sub modNotes_save_Click(sender As Object, e As EventArgs) Handles btnModalNotes.Click
    LeadFunctions.AddNote(Guid.Parse(RouteData.Values("pid")), txtModalNotes.Text)
    PHSuccess.Visible = True
    lblMasterSuccess.Text = "Notes updated"
    listNotes.Rebind()
End Sub

ListNotes数据源定义为：

     Protected Sub ListNotes_NeedDataSource(sender As Object, e As RadListViewNeedDataSourceEventArgs)
     Dim _person As New RiseBI.Lead(CStr(RouteData.Values("pid")))
     ListNotes.DataSource = _person.Notes
End Sub

添加备注时，它会显示在数据库中。但是，即使listview是重新绑定，它也会显示旧数据，而不是新数据。