Ссылка на элемент без общего доступа требует ссылки на объект, пытающейся передать объект в VB.net

Question

Я получаю сообщение об ошибке: ссылка на элемент без общего доступа требует ссылки на объект

при попытке передать объект в VB.net

в строке TBS000.Update (U) возникает ошибка.

Я новичок в этом, что я делаю не так?

Public Class Login
    Private Sub BtnLogIn_Click(sender As Object, e As EventArgs) Handles BtnLogIn.Click
        Dim U As Object
        U = New User(txtUser.ToString, txtPass.ToString)
        TBS000.Update(U)
    End Sub
End Class

Public Class TBS000
    Dim Con As SqlConnection = New SqlConnection
    Public Function Update(User As Object) As String
        Con = ConnectDB()
        .
        .
        .


Public Class User
    Private _userID As String
    Private _password As String
    Public Sub New(ByVal U As String, ByVal P As String)
        UserID = U
        Password = P
    End Sub

    Public Property UserID As String
        Get
            Return _userID
        End Get
        Set(value As String)
            _userID = value
        End Set
    End Property

    Public Property Password As String
        Get
            Return _password
        End Get
        Set(value As String)
            _password = value
        End Set
    End Property
End Class

Answer 1

Подытожим в коде комментарии @ jmcilhinney

Public Class Login
    Private Sub BtnLogIn_Click(sender As Object, e As EventArgs) Handles BtnLogIn.Click
        Dim U As New User(txtUser.ToString, txtPass.ToString)
        Dim TBS As New TBS000()
        Dim RetVal As String = TBS.Update(U)
    End Sub
End Class

Public Class TBS000
    Public Function Update(U As User) As String
        Dim s As String = ""
        Using Con As New SqlConnection("Your connection string")

        End Using
        Return s
    End Function
End Class

Public Class User

    Public Sub New(ByVal U As String, ByVal P As String)
        UserID = U
        Password = P
    End Sub

    Public Property UserID As String
    Public Property Password As String

End Class