vb.net - イベント ハンドラーの境界外のインデックス

Question

への配送料の表示に問題がありますlblshipping.text

Option Explicit On
Option Strict On
Option Infer Off

Public Class frmMain
    Private intMin() As Integer = {1, 11, 51, 101}
    Private intMax() As Integer = {10, 50, 100}
    Private dblShip() As Double = {15, 10, 5, 0}

    Private Sub btnExit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Me.Close()
    End Sub

    Private Sub txtordered_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtOrdered.KeyPress
        ' allows the text box to accept numbers and the Backspace key

        If (e.KeyChar < "0" OrElse e.KeyChar > "9") AndAlso e.KeyChar <> ControlChars.Back Then
            e.Handled = True
        End If
    End Sub

    Private Sub txtordered_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtOrdered.TextChanged
        lblShipping.Text = String.Empty
    End Sub

    Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click

        Dim intOrdered As Integer
        Integer.TryParse(txtOrdered.Text, intOrdered)

        For intIndex As Integer = 0 To 3
            If intOrdered <= 2 Then
                If intOrdered >= intMin(intIndex) And intOrdered <= intMax(intIndex) Then
                    lblShipping.Text = dblShip(intIndex).ToString("C2")
                End If
            End If
            If intIndex = 3 Then
                If intOrdered >= intMin(intIndex) Then
                    lblShipping.Text = dblShip(intIndex).ToString("C2")
                End If
            End If
        Next intIndex
    End Sub
End Class