The Selector Tool throws an access violation exception, when you select Series Marks. The exception is produced in the Selector tool method, DrawSeriesHandle. You can reproduce the problem using the Demo example Welcome !\Tools\Selector Tool or next simple code: 
  public Form1()
        {
            InitializeComponent();
            InitializeChart();
        }

        private void InitializeChart()
        {
            tChart1.Aspect.View3D = true;
             var Series1 = new Steema.TeeChart.Styles.Line(tChart1.Chart);
            Series1.FillSampleValues();
            Series1.Marks.Visible = true;
            var tool1 = new Steema.TeeChart.Tools.Selector(tChart1.Chart); 
        }