Hi Chris,

For a scatter chart both the x and y axis are numeric which is why there is no item, label or series equivalent at each of the tickmarks.This is the reason why the context["ITEM_LABEL"] in the IRenderLabel object of an axis Label is null - you can access only the DATA_VALUE of the axis in the axis' Label. The LabelColumn value could be accessed only per data point value, i.e. when you set a ChartText Labels. Find a sample code demonstrating the ChartText usage at the end of the post.

Regarding custom setting of an axis labels value, you could set a custom range of the axis and use a custom token by IRenderLabel. This allows you to post any string that you want. In the following example, we have demonstrated this to you for the Y axis labels. In the sample we have set the TickMarkStyle to DatInterval of the Y axis and the TickmarkInterval to 1 to be sure that on every tick there will be an equivallent Label data in the table so we could return it. Note that if you comment this two settings for the Y axis, there will have ticks' values with unequivallent Y data value, in which cases we just return the y value for the label. You could return whatever you need as a label.

using System;
using Infragistics.UltraChart.Shared.Styles;
using Infragistics.UltraChart.Resources.Appearance;
using System.Data;
using Infragistics.UltraChart.Resources;
using System.Collections;
using Infragistics.WebUI.UltraWebChart;

public partial class _Default : System.Web.UI.Page
{
    private UltraChart UltraChart1;
    private static DataTable table;
    private static DataTable GetTable()
    {
        if (table == null)
        {
            //Setup DataSource
            Array dataList = Array.CreateInstance(typeof(MyData), 5);
            for (int i = 0; i < 5; i++)
            {
                dataList.SetValue(new MyData(DateTime.Now.AddMonths(i), (double)(i * 10 + i * 0.1), (double)i), i);
            }

            table = new DataTable();
            table.Columns.Add("name", typeof(string));
            table.Columns.Add("Date", typeof(DateTime));
            table.Columns.Add("ValueX", typeof(double));
            table.Columns.Add("ValueY", typeof(double));

            int index = 0;
            foreach (MyData data in dataList)
            {
                table.Rows.Add(new object[] { index.ToString(), data.Date, data.ValueX, data.ValueY });
                index++;
            }
        }

        return table;
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        UltraChart1 = new UltraChart();
        DataTable t = GetTable();
        double minY = (double) t.Rows[0]["ValueY"];// we know that the min value is the first item
        double maxY = (double)t.Rows[t.Rows.Count - 1]["ValueY"]; //and the max is the last

        XYSeries series = new XYSeries();
        series.Data.ValueXColumn = "ValueX";
        series.Data.ValueYColumn = "ValueY";
        series.Data.LabelColumn = "Date";
       
        series.Data.DataSource = t;
        series.DataBind();
        UltraChart1.Series.Add(series);

        //Setup Chart
        UltraChart1.ChartType = ChartType.ScatterChart;
        UltraChart1.ScatterChart.ConnectWithLines = true;
       
        //Setup X Axis
        UltraChart1.Axis.X.Labels.ItemFormatString = "<X_LABEL>";
        UltraChart1.Axis.X.LineThickness = 1;
        UltraChart1.Axis.X.Labels.ItemFormat = AxisItemLabelFormat.Custom;
        UltraChart1.Axis.X.Labels.Orientation = TextOrientation.Horizontal;
        UltraChart1.Axis.X.TickmarkStyle = AxisTickStyle.Smart;
        UltraChart1.Axis.X.TimeAxisStyle.TimeAxisStyle = RulerGenre.Continuous;
        UltraChart1.Axis.X.Labels.Orientation = TextOrientation.VerticalLeftFacing;

        //Setup Y Axis
        UltraChart1.Axis.Y.Labels.ItemFormatString = "<Y_LABEL>";
        UltraChart1.Axis.Y.LineThickness = 1;
        UltraChart1.Axis.Y.Labels.ItemFormat = AxisItemLabelFormat.Custom;
        UltraChart1.Axis.Y.Labels.Orientation = TextOrientation.Horizontal;
        UltraChart1.Axis.Y.RangeType = AxisRangeType.Custom;
        UltraChart1.Axis.Y.RangeMin = minY;
        UltraChart1.Axis.Y.RangeMax = maxY;
        UltraChart1.Axis.Y.TickmarkStyle = AxisTickStyle.DataInterval;
        UltraChart1.Axis.Y.TickmarkInterval = 1;

        //Setup Item Labels
        UltraChart1.ScatterChart.ChartText.Add(new ChartTextAppearance());
        UltraChart1.ScatterChart.ChartText[0].Visible = true;
        UltraChart1.ScatterChart.ChartText[0].Column = -2;
        UltraChart1.ScatterChart.ChartText[0].Row = -2;
        UltraChart1.ScatterChart.ChartText[0].ItemFormatString = "<MY_VALUE>";

        Hashtable MyLabelHashTable = new Hashtable();
        MyLabelHashTable.Add("MY_VALUE", new MyLabelRenderer());
        MyLabelHashTable.Add("X_LABEL", new XAxisRenderer());
        MyLabelHashTable.Add("Y_LABEL", new YAxisRenderer());
        UltraChart1.LabelHash = MyLabelHashTable;

        this.Controls.Add(this.UltraChart1);
    }

    public class XAxisRenderer : IRenderLabel
    {
        #region IRenderLabel Members

        public string ToString(Hashtable context)
        {
            string value = context["DATA_VALUE"].ToString();
            //here the context["ITEM_LABEL"] is null as we have
            //a scatter axis which is a numeric axis
            return value;
        }

        #endregion
    }

    public class YAxisRenderer : IRenderLabel
    {
        #region IRenderLabel Members

        public string ToString(Hashtable context)
        {
            //here the context["ITEM_LABEL"] is null as we have
            //a scatter axis which is a numeric axis
            double value = (double)context["DATA_VALUE"];
            DataTable t = GetTable();
            if (t != null && value != null)
            {
                foreach (DataRow row in t.Rows)
                {
                    if ((double)row["ValueY"] == value)
                    {
                        return row["Date"].ToString();
                    }
                }
            }
           
            return value.ToString();
        }

        #endregion
    }

    public class MyLabelRenderer : IRenderLabel
    {
        public string ToString(Hashtable context)
        {
            string xValue = context["DATA_VALUE_X"].ToString();
            string yValue = context["DATA_VALUE_Y"].ToString();
            return xValue.ToString() + " x " + yValue.ToString();
        }
    }

    class MyData
    {
        public MyData(DateTime date, double valueX, double valueY)
        {
            this.date = date;
            this.valueX = valueX;
            this.valueY = valueY;
        }

        private DateTime date;
        public DateTime Date
        {
            get
            {
                return this.date;
            }
            set
            {
                this.date = value;
            }
        }

        private double valueX;
        public double ValueX
        {
            get
            {
                return this.valueX;
            }
            set
            {
                this.valueX = value;
            }
        }

        private double valueY;
        public double ValueY
        {
            get
            {
                return this.valueY;
            }
            set
            {
                this.valueY = value;
            }
        }
    }
}

Thanks Petia,

Using your example, I was able to map the context["DATA_VALUE"] , which was my X point, to the date value that wanted. I passed my input DataSet to the XAxisRender class as a property and was able to access the Data column that way.