Hi everyone!
First i am a beginner so please dont be too angry if i make mistakes, I am willing to learn. Thanks.
My problem: I am learning VB.Net 2003, I am creating a program to save daily customer numbers with the date(now). I attach code! I have problem to sae the lstCustomerStatistic to a txt.file, and later read it agin in for further use.

Public Class frmCustomerStatistic
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()

        'This call is required by the Windows Form Designer.

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
            End If
        End If
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    Friend WithEvents MainMenu1 As System.Windows.Forms.MainMenu
    Friend WithEvents mnuFile As System.Windows.Forms.MenuItem
    Friend WithEvents MenuItem3 As System.Windows.Forms.MenuItem
    Friend WithEvents MenuItem4 As System.Windows.Forms.MenuItem
    Friend WithEvents mnuFileOpen As System.Windows.Forms.MenuItem
    Friend WithEvents mnuFileSave As System.Windows.Forms.MenuItem
    Friend WithEvents mnuFileExit As System.Windows.Forms.MenuItem
    Friend WithEvents lstCustomerStatistic As System.Windows.Forms.ListBox
    Friend WithEvents txtCustomerNumber As System.Windows.Forms.TextBox
    Friend WithEvents lblDate As System.Windows.Forms.Label
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents btnAddToList As System.Windows.Forms.Button
    Friend WithEvents btnClearEntry As System.Windows.Forms.Button
    Friend WithEvents btnEnterCustomerNumber As System.Windows.Forms.Button
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents Label3 As System.Windows.Forms.Label
    Friend WithEvents dlgSave As System.Windows.Forms.SaveFileDialog
    Friend WithEvents dlgOpen As System.Windows.Forms.OpenFileDialog
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.btnAddToList = New System.Windows.Forms.Button
        Me.MainMenu1 = New System.Windows.Forms.MainMenu
        Me.mnuFile = New System.Windows.Forms.MenuItem
        Me.mnuFileOpen = New System.Windows.Forms.MenuItem
        Me.mnuFileSave = New System.Windows.Forms.MenuItem
        Me.MenuItem3 = New System.Windows.Forms.MenuItem
        Me.MenuItem4 = New System.Windows.Forms.MenuItem
        Me.mnuFileExit = New System.Windows.Forms.MenuItem
        Me.dlgSave = New System.Windows.Forms.SaveFileDialog
        Me.dlgOpen = New System.Windows.Forms.OpenFileDialog
        Me.lstCustomerStatistic = New System.Windows.Forms.ListBox
        Me.txtCustomerNumber = New System.Windows.Forms.TextBox
        Me.lblDate = New System.Windows.Forms.Label
        Me.btnClearEntry = New System.Windows.Forms.Button
        Me.Label1 = New System.Windows.Forms.Label
        Me.btnEnterCustomerNumber = New System.Windows.Forms.Button
        Me.Label2 = New System.Windows.Forms.Label
        Me.Label3 = New System.Windows.Forms.Label
        Me.btnAddToList.Enabled = False
        Me.btnAddToList.Location = New System.Drawing.Point(8, 192)
        Me.btnAddToList.Name = "btnAddToList"
        Me.btnAddToList.Size = New System.Drawing.Size(128, 32)
        Me.btnAddToList.TabIndex = 0
        Me.btnAddToList.Text = "&Add To List"
        Me.MainMenu1.MenuItems.AddRange(New System.Windows.Forms.MenuItem() {Me.mnuFile})
        Me.mnuFile.Index = 0
        Me.mnuFile.MenuItems.AddRange(New System.Windows.Forms.MenuItem() {Me.mnuFileOpen, Me.mnuFileSave, Me.MenuItem3, Me.MenuItem4, Me.mnuFileExit})
        Me.mnuFile.Text = "&File"
        Me.mnuFileOpen.Index = 0
        Me.mnuFileOpen.Text = "&Open"
        Me.mnuFileSave.Enabled = False
        Me.mnuFileSave.Index = 1
        Me.mnuFileSave.Text = "&Save"
        Me.MenuItem3.Index = 2
        Me.MenuItem3.Text = "-"
        Me.MenuItem4.Index = 3
        Me.MenuItem4.Text = ""
        Me.mnuFileExit.Index = 4
        Me.mnuFileExit.Text = "&Exit"
        Me.dlgSave.DefaultExt = "txt"
        Me.dlgSave.Filter = "Text Files(*.txt)|*.txt"
        Me.dlgSave.Title = "Save File"
        Me.dlgOpen.Filter = "Text Files(*.txt)|*.txt"
        Me.dlgOpen.Title = "Open File"
        Me.lstCustomerStatistic.Location = New System.Drawing.Point(144, 136)
        Me.lstCustomerStatistic.Name = "lstCustomerStatistic"
        Me.lstCustomerStatistic.Size = New System.Drawing.Size(256, 212)
        Me.lstCustomerStatistic.TabIndex = 2
        Me.txtCustomerNumber.Location = New System.Drawing.Point(144, 64)
        Me.txtCustomerNumber.Name = "txtCustomerNumber"
        Me.txtCustomerNumber.Size = New System.Drawing.Size(256, 20)
        Me.txtCustomerNumber.TabIndex = 3
        Me.txtCustomerNumber.Text = ""
        Me.lblDate.BackColor = System.Drawing.Color.White
        Me.lblDate.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.lblDate.Location = New System.Drawing.Point(144, 16)
        Me.lblDate.Name = "lblDate"
        Me.lblDate.Size = New System.Drawing.Size(256, 23)
        Me.lblDate.TabIndex = 4
        Me.lblDate.TextAlign = System.Drawing.ContentAlignment.MiddleLeft
        Me.btnClearEntry.Enabled = False
        Me.btnClearEntry.Location = New System.Drawing.Point(8, 248)
        Me.btnClearEntry.Name = "btnClearEntry"
        Me.btnClearEntry.Size = New System.Drawing.Size(128, 32)
        Me.btnClearEntry.TabIndex = 5
        Me.btnClearEntry.Text = "&Clear Entry"
        Me.Label1.Location = New System.Drawing.Point(16, 16)
        Me.Label1.Name = "Label1"
        Me.Label1.TabIndex = 6
        Me.Label1.Text = "Date:"
        Me.btnEnterCustomerNumber.Location = New System.Drawing.Point(8, 136)
        Me.btnEnterCustomerNumber.Name = "btnEnterCustomerNumber"
        Me.btnEnterCustomerNumber.Size = New System.Drawing.Size(128, 32)
        Me.btnEnterCustomerNumber.TabIndex = 7
        Me.btnEnterCustomerNumber.Text = "&Enter Customer Number"
        Me.Label2.Location = New System.Drawing.Point(144, 104)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(64, 23)
        Me.Label2.TabIndex = 8
        Me.Label2.Text = "Date:"
        Me.Label2.TextAlign = System.Drawing.ContentAlignment.BottomLeft
        Me.Label3.Location = New System.Drawing.Point(264, 104)
        Me.Label3.Name = "Label3"
        Me.Label3.Size = New System.Drawing.Size(104, 23)
        Me.Label3.TabIndex = 9
        Me.Label3.Text = "Customer served:"
        Me.Label3.TextAlign = System.Drawing.ContentAlignment.BottomLeft
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(410, 361)
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle
        Me.Menu = Me.MainMenu1
        Me.Name = "frmCustomerStatistic"
        Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
        Me.Text = "Customer Statistic"

    End Sub

#End Region
    Dim noCustomerRecords As Integer
    Dim arrData(364) As String
    Dim arrDate(364) As String
    Dim i As Integer

    Private Sub frmCustomerStatistic_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
        lblDate.Text = Format(Now, "ddd dd MMMM yyyy".ToString)
        btnAddToList.Enabled = False

    End Sub

    Private Sub txtCustomerNumber_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtCustomerNumber.KeyPress
        Dim KeyAscii As Integer
        KeyAscii = Asc(e.KeyChar)
        'only allow numbers, backspace or enter
        Select Case KeyAscii
            Case Asc("0") To Asc("9"), Asc(ControlChars.Back)
                'acceptable keystrokes
                e.Handled = False
                btnAddToList.Enabled = True
            Case Asc(ControlChars.Cr)
                'enter key or click on Add To List Button
                btnAddToList.Enabled = False
            Case Else
                e.Handled = True
                MsgBox("Please enter only Customer numbers!", , "Error")
                btnAddToList.Enabled = False

        End Select

    End Sub

    Private Sub btnEnterCustomerNumber_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEnterCustomerNumber.Click
        btnEnterCustomerNumber.Enabled = True

    End Sub

    Private Sub btnAddToList_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddToList.Click
        'Add Date and Customer number to the List
        lstCustomerStatistic.Items.Add((lblDate.Text) + ("         ") + (txtCustomerNumber.Text))
        mnuFileSave.Enabled = True
        btnClearEntry.Enabled = True
        'test if customer entry is already made
        If lstCustomerStatistic.Items.Count = +1 Then
            btnAddToList.Enabled = False
        End If

    End Sub

    Private Sub btnClearEntry_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClearEntry.Click
        Dim Ind As Integer
        'Get Index
        Ind = lstCustomerStatistic.SelectedIndex
        'Make sure list item is selected
        If Ind >= 0 Then
            'Remove it from list box
        End If
        If btnClearEntry.Enabled = True Then
            btnAddToList.Enabled = False
            'Clear text box
            txtCustomerNumber.Text = ""
            'Show message to enter data
            MsgBox("Please click the Enter Customer Number button!", , "Enter Data")

        End If
    End Sub

    Private Sub lstCustomerStatistic_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstCustomerStatistic.SelectedIndexChanged

    End Sub

    Private Sub mnuFileSave_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles mnuFileSave.Click
            'code to save file
        Catch ex1 As Data.ReadOnlyException
            MsgBox("Please change the Read only property!", , "Error")
        Catch ex2 As Exception
            MsgBox("Error while saving your Data!", , "Contact your Administrator")
        End Try

        'Save Data
        If dlgSave.ShowDialog() = DialogResult.OK Then
            FileOpen(1, dlgSave.FileName, OpenMode.Output)
        End If
    End Sub
End Class

I try to solve this problem now for 2 weeks nearly, PLease give a push in the right direction
Thanks a lot

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