AgileNET v6.6.0.4.2

private void btn_Click(object sender, EventArgs e)
{
	if (string.IsNullOrEmpty(txt.Text) || !txt.Text[0].Equals(txt.Text[txt.Text.Length - 1]))
	{
		MessageBox.Show("please enter a valid serial");
		return;
	}
	else d0();
}

initial