How to add a public member to a User Control?

Hi Experts,
I'm trying to add a public member to a User Control.
When I run this code and click the button, I get "Public member 'txtValue' on type 'Button' not found."
Any Idea how to do this?
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THE FORM
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Partial Public Class ModularPortal : Inherits Form
    Public Sub New()
        InitializeComponent()
    End Sub

    Private Sub ModularPortal_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
        Create_buttons()
        Create_buttons()
    End Sub
    Private MNButtonCount As Integer = 0
    Private Sub Create_buttons()
        Dim NewButton As New button_panel()
        NewButton.Location = New System.Drawing.Point(12, 204 + MNButtonCount)
        AddHandler NewButton.Click, AddressOf alfa
        AddHandler NewButton.Button_panel_Click, AddressOf alfa
        Me.mnupanel.Controls.Add(NewButton)
        MNButtonCount += 100
    End Sub
    Public Sub alfa(ByVal sender As Object, ByVal e As EventArgs)
        sender.txtValue = "OK"
    End Sub

End Class
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THE USER CONTROL
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Public Class button_panel
    Inherits System.Windows.Forms.UserControl

    Public Event Button_panel_Click(ByVal sender As Object, ByVal e As EventArgs)

    Public Property txtValue() As String
        Get
            Return TextBox1.Text
        End Get
        Set(ByVal value As String)
            TextBox1.Text = value
        End Set
    End Property

    Public Sub Button1_Click(ByVal sender As Object, ByVal e As eventargs) Handles button1.click

        RaiseEvent Button_panel_Click(sender, e)
    End Sub
End ClassStart Free Trial