SQL Server обновляет столбец отметки времени

В моей базе данных есть столбец timestamp . Мне нужно обновить строку в таблице и обновить столбец отметка времени . Когда я запускаю команду обновления, я получаю: Есть ли другой способ установить свойство CurrentPrincipal для всех потоков в приложении?

Исходный код для воспроизведения проблемы:

Imports System.Security.Principal
Imports System.Threading

Public Class Form1

  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Dim lThread As New Thread(AddressOf doLogin)
    lThread.Start()
  End Sub

  Private Sub doLogin()
     Invoke(New Action(AddressOf setPrincipal))
  End Sub

  Private Sub setPrincipal()
     My.User.CurrentPrincipal = New CustomPrincipal
     MsgBox(My.User.CurrentPrincipal.Identity.AuthenticationType) ' Custom
  End Sub

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    MsgBox(My.User.CurrentPrincipal.Identity.AuthenticationType) ' Default
  End Sub
End Class

Public Class CustomPrincipal
  Implements IPrincipal

  Public ReadOnly Property Identity() As IIdentity Implements IPrincipal.Identity
    Get
      Return New CustomIdentity()
    End Get
  End Property

  Public Function IsInRole(ByVal role As String) As Boolean Implements IPrincipal.IsInRole
     Return True
  End Function
End Class

Public Class CustomIdentity
  Implements IIdentity

  Public ReadOnly Property AuthenticationType() As String Implements IIdentity.AuthenticationType
    Get
      Return "Custom"
    End Get
  End Property

  Public ReadOnly Property IsAuthenticated() As Boolean Implements IIdentity.IsAuthenticated
    Get
      Return True
    End Get
  End Property

  Public ReadOnly Property Name() As String Implements IIdentity.Name
    Get
      Return "CustomName"
    End Get
  End Property
End Class