okay, so the relationship between the row in the datatable and the context["DATA_ROW"] isn't direct, like it is for charts which are based on tabular data structures.

i think the best way to get your real row index back is by setting a primary key on your source DataTable and then using its Rows.Find method to get the row back.

here's some sample code:

 private void Form1_Load(object sender, EventArgs e)
        {
            this.ultraChart1.ChartType = ChartType.TreeMapChart;
            DataTable table = new DataTable();
            table.Columns.Add("Category", typeof(string));
            table.Columns.Add("Name", typeof(string));
            table.Columns.Add("UnitPrice", typeof(double));
            table.Columns.Add("YearlySales", typeof(double));
            table.Rows.Add(new object[ { "Fruit", "Apples", 3, 200 });
            table.Rows.Add(new object[ { "Fruit", "Bananas", 2, 100 });
            table.Rows.Add(new object[ { "Fruit", "Oranges", 1, 50 });
            table.Rows.Add(new object[ { "Dairy", "Milk", 4, 20 });
            table.Rows.Add(new object[ { "Dairy", "Cheese", 5, 10 });
            table.Rows.Add(new object[ { "Meat", "Steak", 10, 150 });
            table.Rows.Add(new object[ { "Meat", "Chicken", 8, 35 });
            table.PrimaryKey = new DataColumn[ { table.Columns["Name"] };
            this.ultraChart1.Data.DataSource = table;
            this.ultraChart1.Data.DataBind();

            Hashtable labelRenderers = new Hashtable();
            labelRenderers.Add("MY_TREE_LABEL", new TreeMapTooltipRenderer(table));
            this.ultraChart1.LabelHash = labelRenderers;
            this.ultraChart1.Tooltips.FormatString = "<MY_TREE_LABEL>";
            
        }
        internal class TreeMapTooltipRenderer : IRenderLabel
        {
            internal TreeMapTooltipRenderer(DataTable table)
            {
                this.Table = table;
            }
            private DataTable Table { get; set; }
            string IRenderLabel.ToString(Hashtable context)
            {
                if (context.ContainsKey("ShapeLabel"))
                {
                    int realRowIndex = this.Table.Rows.IndexOf(this.Table.Rows.Find(context["ShapeLabel"]));
                    return "Row Number " + realRowIndex;
                }
                return "";
            }
        }

David

Thanks for your reply. Yes i am using context["DATA_ROW"]. I am attaching the code of IRenderClass which i used here.

using System;

using System.Collections.Generic;

using System.Text;

using System.Collections;

using Infragistics.UltraChart.Resources;

using System.Data;

public class RenderLabel:IRenderLabel

System.Text.StringBuilder ReturnValue;

ReturnValue.Append("Department:");

ReturnValue.Append("\n");

ReturnValue.Append(DR["ItemNumber"]);

ReturnValue.Append("Stock:");

ReturnValue.Append("\n");

ReturnValue.Append(DR["Description"]);