[VB2008] โปรแกรมส่ง Mail (อีเมล์) ที่ผมทำมีปัญหาครับ มาช่วยแก้ไขโค้ดให้ที่ครับ

Imports System.IO
Imports System.Net.Mail
Public Class Form1

    Private Sub Label2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

    End Sub

    Private Sub Label5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label5.Click

    End Sub

    Private Sub MenuStrip1_ItemClicked(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ToolStripItemClickedEventArgs) Handles MenuStrip1.ItemClicked

    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        TextBox4.PasswordChar = "*"
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If TextBox1.Text = "" Or TextBox2.Text = "" Then
            MsgBox("กรุณาใส่ข้อมูลให้ครบ")

        Else



            Dim htmail As New MailMessage
            With htmail
                .From = New MailAddress("" + ListBox1.Text + "")
                .To.Add("" + ListBox1.Text + "")
                .Subject = ("" + TextBox2.Text + "")
                .Body = ("To You : " & TextBox1.Text)
            End With
            Dim SMTPServer As New SmtpClient("" + ComboBox1.Text + "")
            SMTPServer.Port = 587
            SMTPServer.Credentials = New System.Net.NetworkCredential("" + TextBox3.Text + "", "" + TextBox4.Text + "")
            SMTPServer.EnableSsl = True
            SMTPServer.Send(htmail)

            Try

                MsgBox("ส่งสำเร็จ")
            Catch ex As Exception
                MsgBox("Failed Login")
            End Try

        End If

    End Sub

    
    Private Sub เพมรายชอผรบToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles เพมรายชอผรบToolStripMenuItem.Click
        OpenFileDialog1.DefaultExt = "*.*"
        OpenFileDialog1.AddExtension = True

        OpenFileDialog1.Filter = "Text File|*.txt"



        If OpenFileDialog1.ShowDialog = DialogResult.OK Then
            TextBox5.Text = OpenFileDialog1.FileName

        End If

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        If TextBox5.Text = "" Then
            MsgBox("กรุณา Add File")

        Else
            Dim FileToLoad As String = "" + TextBox5.Text + ""
            Dim fs As FileStream = New FileStream(FileToLoad, FileMode.Open)
            Dim sr As StreamReader = New StreamReader(fs)
            Do While Not sr.EndOfStream
                ListBox1.Items.Add(sr.ReadLine)
            Loop
            sr.Close()
            fs.Close()
            TextBox5.Clear()
        End If
    End Sub

    
    
End Class