Visual Basic.NET - No puedo volcar un valor en un TextBox desde un SubProceso

Imports System.IO

Imports System.Text

Imports DPFP

Imports DPFP.Capture

Imports MySql.Data.MySqlClient

Imports System.Data

Imports System.Data.SqlClient

Public Class Busqueda

    Implements DPFP.Capture.EventHandler

    Private template As DPFP.Template

    Private captura As DPFP.Capture.Capture

    Private verificador As DPFP.Verification.Verification

    Protected Overridable Sub Init()

        Try

            captura = New Capture()

            If Not captura Is Nothing Then

                captura.EventHandler = Me

                verificador = New Verification.Verification()

                template = New Template()

            Else

                MessageBox.Show("No se pudo instanciar la captura")

            End If

        Catch ex As Exception

            MessageBox.Show("No se pudo instanciar la captura")

        End Try

    End Sub

    Protected Sub iniciarCaptura()

        If Not captura Is Nothing Then

            Try

                captura.StartCapture()

            Catch ex As Exception

                MessageBox.Show("No se pudo instanciar la captura")

            End Try

        End If

    End Sub

    Protected Sub pararCaptura()

        If Not captura Is Nothing Then

            Try

                captura.StopCapture()

            Catch ex As Exception

                MessageBox.Show("No se pudo detener la captura")

            End Try

        End If

    End Sub

    Private Sub ponerImagen(ByVal bmp)

        imagenHuella.Image = bmp

    End Sub

    Private Sub ponerMensaje(ByVal texto)

        TextBox1.Text = texto '------------------------> DA ERROR

    End Sub

    Protected Function ConvertirSampleAMapaDeBits(ByVal Sample As DPFP.Sample)

        Dim convertidor As New DPFP.Capture.SampleConversion()

        Dim mapaBits As Bitmap = Nothing

        convertidor.ConvertToPicture(Sample, mapaBits)

        Return mapaBits

    End Function

    Protected Function extraerCaracteristicas(ByVal Sample As DPFP.Sample, ByVal Purpose As DPFP.Processing.DataPurpose) As DPFP.FeatureSet

        Dim extractor As New DPFP.Processing.FeatureExtraction()

        Dim alimentacion As DPFP.Capture.CaptureFeedback = DPFP.Capture.CaptureFeedback.None

        Dim caracteristicas As New DPFP.FeatureSet()

        extractor.CreateFeatureSet(Sample, Purpose, alimentacion, caracteristicas)

        If (alimentacion = DPFP.Capture.CaptureFeedback.Good) Then

            Return caracteristicas

        Else

            Return Nothing

        End If

    End Function

    Public Sub OnComplete(Capture As Object, ReaderSerialNumber As String, Sample As Sample) Implements EventHandler.OnComplete

        ponerMensaje("prueba")

        ponerImagen(ConvertirSampleAMapaDeBits(Sample))

        Dim caracteristicas As DPFP.FeatureSet = extraerCaracteristicas(Sample, DPFP.Processing.DataPurpose.Verification)

        If Not caracteristicas Is Nothing Then

            Dim result As New DPFP.Verification.Verification.Result()

            Dim builderconex As New MySqlConnectionStringBuilder()

            builderconex.Server = "127.0.0.1"

            builderconex.UserID = "root"

            builderconex.Password = ""

            builderconex.Database = "fingerprint"

            Dim conexion As New MySqlConnection(builderconex.ToString())

            conexion.Open()

            Dim cmd As New MySqlCommand()

            cmd = conexion.CreateCommand

            cmd.CommandText = "SELECT * FROM usuarios"

            Dim read As MySqlDataReader

            read = cmd.ExecuteReader()

            Dim verificado As Boolean = False

            Dim nombre As String = ""

            Dim cedula As String = ""

            Dim dedo As String = ""

            While (read.Read())

                nombre = read("Nombre")

                cedula = read("Cedula")

                dedo = read("Dedo")

                Dim memoria As New MemoryStream(CType(read("huella"), Byte()))

                template.DeSerialize(memoria.ToArray())

                verificador.Verify(caracteristicas, template, result)

                If (result.Verified) Then

                    nombre = read("nombre")

                    cedula = read("Cedula")

                    dedo = read("Dedo")

                    verificado = True

                    Exit While

                End If

            End While

            If (verificado) Then

                Dim mensaje As String

                mensaje = String.Concat(nombre, " ", cedula, " ", dedo)

                'txtLectura.Text = "Hola Mundo"

                'Me.txtNombre = mensaje

                MessageBox.Show(mensaje)  '----------------> INVOCA A UNA SUB PARA VER SI LOGRA SOLUCIONAR EL PROBLEMA

                ponerMensaje(mensaje)

                'MessageBox.Show(nombre)

                'MessageBox.Show(cedula)

                'MessageBox.Show(dedo)

            Else

                MessageBox.Show("No se encontro ningun registro")

            End If

            read.Dispose()

            cmd.Dispose()

            conexion.Close()

            conexion.Dispose()

        End If

    End Sub

    Public Sub OnFingerGone(Capture As Object, ReaderSerialNumber As String) Implements EventHandler.OnFingerGone

    End Sub

    Public Sub OnFingerTouch(Capture As Object, ReaderSerialNumber As String) Implements EventHandler.OnFingerTouch

    End Sub

    Public Sub OnReaderConnect(Capture As Object, ReaderSerialNumber As String) Implements EventHandler.OnReaderConnect

    End Sub

    Public Sub OnReaderDisconnect(Capture As Object, ReaderSerialNumber As String) Implements EventHandler.OnReaderDisconnect

    End Sub

    Public Sub OnSampleQuality(Capture As Object, ReaderSerialNumber As String, CaptureFeedback As CaptureFeedback) Implements EventHandler.OnSampleQuality

    End Sub

    Private Sub Busqueda_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Init()

        iniciarCaptura()

    End Sub

    Private Sub Busqueda_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing

        pararCaptura()

    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles btnEnrolar.Click

        pararCaptura()

        Dim ventanaEnrolar As New ventanaEnrolar()

        ventanaEnrolar.ShowDialog()

    End Sub

End Class

Friend Class Enrolar

    Public Sub New()

    End Sub

End Class