Private Sub tnBildLaden_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles btnBildLaden.Click
        If Not IsNothing(PictureBox1.Image) Then
            PictureBox1.Image.Dispose()
            PictureBox1.Image = Nothing
        End If
        PictureBox1.Image = New Bitmap("D:\" & lblBildname.Text & ".jpg")
        lblBildname.Text += 1
    End Sub