hartAnalysis_BLL objBLL = new ChartAnalysis_BLL();
DataTable dt = objBLL.GetMonthlySSMTotalQuantityImported(arrParameters);

// Create new chart
RadChart2.ChartTitle.TextBlock.Appearance.TextProperties.Font = new System.Drawing.Font(RadChart2.ChartTitle.TextBlock.Appearance.TextProperties.Font.FontFamily, 11, System.Drawing.FontStyle.Bold);
RadChart2.ChartTitle.TextBlock.Text = "Extended Monthly SSM Total Quantity Imported \n(" + ssm[0] + ")";
RadChart2.Width = AppConstants.CONST_CHART_WIDTH;
RadChart2.ChartTitle.Visible = true;
RadChart2.Chart.DefaultType = ChartSeriesType.Line;
RadChart2.PlotArea.Appearance.Dimensions.Margins.Left = Telerik.Charting.Styles.Unit.Percentage(10);
RadChart2.PlotArea.Appearance.Dimensions.Margins.Right = Telerik.Charting.Styles.Unit.Percentage(15);
RadChart2.PlotArea.Appearance.Dimensions.Margins.Bottom = Telerik.Charting.Styles.Unit.Percentage(30);

RadChart2.DataManager.ValuesXColumn = "Date";
RadChart2.DataManager.ValuesYColumns = new string[1] { "SSM Quantity" };
RadChart2.IntelligentLabelsEnabled = true;
RadChart2.DataSource = dt;
RadChart2.DataBind();
RadChart2.Skin = AppConstants.CONST_TELERIK_CHARTSKIN;

RadChart2.PlotArea.XAxis.Clear();
RadChart2.PlotArea.XAxis.IsZeroBased = false;
RadChart2.PlotArea.XAxis.AutoScale = false;
RadChart2.PlotArea.XAxis.Appearance.ValueFormat = ChartValueFormat.ShortDate;
RadChart2.PlotArea.XAxis.Appearance.CustomFormat = "MMM yy";
RadChart2.PlotArea.XAxis.AxisLabel.Visible = true;
RadChart2.PlotArea.XAxis.AxisLabel.TextBlock.Text = "Month \n(" + AppFunctions.GetDisclaimer() + ")";
RadChart2.PlotArea.XAxis.AxisLabel.TextBlock.Appearance.TextProperties.Color = System.Drawing.Color.Black;
RadChart2.PlotArea.XAxis.Appearance.LabelAppearance.RotationAngle = -45;

RadChart2.PlotArea.YAxis.AxisLabel.Visible = true;
RadChart2.PlotArea.YAxis.AxisLabel.TextBlock.Text = "Total Quantity of SSM Imported (" + dt.Rows[0]["UOM"] + ")";
RadChart2.PlotArea.YAxis.AxisLabel.TextBlock.Appearance.TextProperties.Color = System.Drawing.Color.Black;

RadChart2.Series.GetSeries(0).Appearance.PointMark.Dimensions.Width = 1;
RadChart2.Series.GetSeries(0).Appearance.PointMark.Dimensions.Height = 1;
RadChart2.Series.GetSeries(0).Appearance.PointMark.FillStyle.MainColor = System.Drawing.Color.Black;
RadChart2.Series.GetSeries(0).Appearance.PointMark.FillStyle.FillType = FillType.Solid;
RadChart2.Series.GetSeries(0).Appearance.PointMark.Visible = true;
RadChart2.Series.GetSeries(0).Appearance.LineSeriesAppearance.Color = System.Drawing.Color.Orange;
RadChart2.Series.GetSeries(0).Appearance.LineSeriesAppearance.Width = 3;

int intYear = dt_SelDateFrom.Year;
int intMonth = dt_SelDateFrom.Month;
DateTime start = new DateTime(intYear, intMonth, 1);
TimeSpan ts = dt_SelDateTo - dt_SelDateFrom;
int intMthDiff = Convert.ToInt32(Math.Ceiling((ts.TotalDays / 30)));

for (int i = 0; i < intMthDiff; i++)
{
    ChartAxisItem item = new ChartAxisItem();
    item.Value = (decimal)start.AddMonths(i).ToOADate();
    RadChart2.PlotArea.XAxis.AddItem(item);
}

DataTable dt_avg = objBLL.GetSSMTotalImportedLastYearAverage(arrParameters);

// Define chart series
ChartSeries avg_series = new ChartSeries();
avg_series.Appearance.LabelAppearance.Visible = false;
avg_series.Name = "Last Year Average";
avg_series.Type = ChartSeriesType.Line;
avg_series.Appearance.PointMark.Dimensions.Width = 1;
avg_series.Appearance.PointMark.Dimensions.Height = 1;
avg_series.Appearance.PointMark.FillStyle.MainColor = System.Drawing.Color.Black;
avg_series.Appearance.PointMark.FillStyle.FillType = FillType.Solid;
avg_series.Appearance.PointMark.Visible = true;
avg_series.Appearance.LineSeriesAppearance.Color = System.Drawing.Color.Red;

foreach (DataRow row in dt_avg.Rows)
{
    foreach (DataColumn col in dt_avg.Columns)
    {
        Decimal dec_data = Convert.ToDecimal(row[col]);
        Double dbl_data = Convert.ToInt32(dec_data);
        avg_series.AddItem(dbl_data);
    }
}

RadChart2.AddChartSeries(avg_series);

ArrayList arrParameterBaseline = new ArrayList();
arrParameterBaseline.Add(dt_SelBaselineFrom);
arrParameterBaseline.Add(dt_SelBaselineTo);
arrParameterBaseline.Add(dt_SelSSMSeqID);
SqlDataReader dr_baseline = objBLL.GetSSMTotalImportedBaseline(arrParameterBaseline);

ChartSeries baseline_series = new ChartSeries();
baseline_series.Appearance.LabelAppearance.Visible = false;
baseline_series.Name = "Baseline Average";
baseline_series.Type = ChartSeriesType.Line;
baseline_series.Appearance.PointMark.Dimensions.Width = 1;
baseline_series.Appearance.PointMark.Dimensions.Height = 1;
baseline_series.Appearance.PointMark.FillStyle.MainColor = System.Drawing.Color.Black;
baseline_series.Appearance.PointMark.FillStyle.FillType = FillType.Solid;
baseline_series.Appearance.PointMark.Visible = true;
baseline_series.Appearance.LineSeriesAppearance.Color = System.Drawing.Color.Chartreuse;

Double dbl_baseline = 0;

if (dr_baseline == null)
{
    dbl_baseline = 0;
}
else
{
    try
    {
        while (dr_baseline.Read())
        {
            if (dr_baseline["TotalImportedBaseline"] == DBNull.Value)
                dbl_baseline = 0;
            else
            {
                Decimal dec_baseline = dr_baseline.GetDecimal(dr_baseline.GetOrdinal("TotalImportedBaseline"));
                dbl_baseline = Convert.ToDouble(dec_baseline);
            }
        }
    }
    catch (Exception ex)
    {
        AppFunctions.SetMessageError(this.Page, AppConstants.CONST_ERROR_LOAD_CHART);
        AppFunctions.ErrorLog(ex);
    }
    finally
    {
        if (dr_baseline != null)
        {
            dr_baseline.Close();
            dr_baseline.Dispose();
        }
    }
}

for (int i = 0; i < intMthDiff; i++)
{
    baseline_series.AddItem(dbl_baseline);
}

RadChart2.AddChartSeries(baseline_series);

Panel1.Controls.Add(RadChart2);

}
catch (Exception ex)
{
    AppFunctions.SetMessageError(this.Page, AppConstants.CONST_ERROR_LOAD_CHART);
    AppFunctions.ErrorLog(ex);
}

<script>
    function OnKendoWidgetInitializing(sender, args) {
        var series = args.series[0]
        series.highlight = series.highlight || {};
        series.highlight.inactiveOpacity = 0.2
    }
</script>
<telerik:RadHtmlChart ID="RadHtmlChart5" runat="server" BorderColor="Fuchsia" BorderStyle="Solid" BorderWidth="1px">
    <ClientEvents OnKendoWidgetInitializing="OnKendoWidgetInitializing" />
    <PlotArea>

        <Series>
            <telerik:PieSeries StartAngle="90">
                <%-- This is how it should be configured after the feature request --%>
                <%--<HighlightAppearance InactiveOpacity="0.2" />--%>

                <SeriesItems>
                    <telerik:PieSeriesItem Name="Slice1" Y="60"></telerik:PieSeriesItem>
                    <telerik:PieSeriesItem Name="Slice2" Y="40"></telerik:PieSeriesItem>
                </SeriesItems>
            </telerik:PieSeries>
        </Series>
    </PlotArea>
</telerik:RadHtmlChart>

            function chartLoad(chart, args) {

                chart.get_kendoWidget().setOptions({ title: { font: "20px sans-serif; font-weight: 300" }});

            }