I am trying to do a search function for a listbox and I have the search working but it is case-sensitive. How do you make it non?

Code:
 For i As Integer = 0 To FrmMain.LstBxMovie.Items.Count - 1
            If Not cancelled Then
                If FrmMain.LstBxMovie.Items(i).ToString.Contains(sSearchString) Then
                    FrmMain.LstBxMovie.SelectedIndex = i
                    'MsgBox(FrmMain.tvwMain.SelectedNode)

                    response = MsgBox("click ok to continue search, or cancel to abort search", MsgBoxStyle.OkCancel Or MsgBoxStyle.DefaultButton1 Or MsgBoxStyle.Question)
                    If response = MsgBoxResult.Cancel Then cancelled = True
                End If
            End If
        Next