Private Sub btnAssinar_Click(sender As Object, e As EventArgs) If openFileDialog1.ShowDialog() = DialogResult.OK Then btnAssinar.Enabled = False Dim nfse As New asscshnfse.asscshnfse() Dim tmp As String = nfse.AssinarArquivoXML(openFileDialog1.FileName, "TipoRPS") MessageBox.Show(tmp) btnAssinar.Enabled = True End If End Sub