Разбить строку на подстроки - Visual Basic .NET (64140)

 
    Private PATH_USERS As String = "C:\temp\USERS.txt"
    Private PATH_BLOCK As String = "C:\temp\BLOCK.txt" 'путь'
    Private FILE_BLOCK() As String
    Private FILE() As String
    Private counter, cMin, cMax As Integer

 Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click 'вперед'
        If counter = cMax Then Exit Sub
        counter += 1
        TextBox1.Text = FILE(counter)
 
    End Sub
 
 Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 'назад'
        If counter = cMin Then Exit Sub
        counter -= 1
        TextBox1.Text = FILE(counter)
    End Sub
 
Private Sub Form6_Load(sender As Object, e As EventArgs) Handles MyBase.Load 'загрузка формы'
        FILE = IO.File.ReadAllLines(PATH_USERS, System.Text.Encoding.Default) 'массив строк'
        FILE_BLOCK = IO.File.ReadAllLines(PATH_BLOCK, System.Text.Encoding.Default)
        cMin = 0 'Минимальное значение счетчика'
        cMax = FILE.Length - 1 'Максимальное значение счетчика'
        counter = 0 'Начальное значение'
        TextBox1.Text = FILE(counter) 'Показывается самая первая запись'
    End Sub