This does indeed work with composite charts. If you're experiencing problems, please provide sample code to help us reproduce the problem. Here's a sample that does work with a custom tooltip renderer:

ultraChart1.ChartType = ChartType.Composite;
ChartArea area = new ChartArea();
ultraChart1.CompositeChart.ChartAreas.Add(area);

NumericSeries series = new NumericSeries();
series.Points.Add(new NumericDataPoint(0, "item1", false));
series.Points.Add(new NumericDataPoint(5, "item2", false));
series.Points.Add(new NumericDataPoint(2, "item3", false));
series.Points.Add(new NumericDataPoint(7, "item4", false));
series.Points.Add(new NumericDataPoint(4, "item5", false));
ultraChart1.CompositeChart.Series.Add(series);

AxisItem xAxis = new AxisItem(ultraChart1, AxisNumber.X_Axis);
xAxis.SetLabelAxisType = SetLabelAxisType.ContinuousData;
xAxis.DataType = AxisDataType.String;

AxisItem yAxis = new AxisItem(ultraChart1, AxisNumber.Y_Axis);
yAxis.DataType = AxisDataType.Numeric;

area.Axes.Add(xAxis);
area.Axes.Add(yAxis);

ChartLayerAppearance layer = new ChartLayerAppearance();
layer.ChartType = ChartType.LineChart;
layer.Series.Add(series);
layer.ChartArea = area;
layer.AxisX = xAxis;
layer.AxisY = yAxis;
ultraChart1.CompositeChart.ChartLayers.Add(layer);

Hashtable labelHash = new Hashtable();
labelHash.Add("CUSTOM", new MyLabelRenderer());
ultraChart1.LabelHash = labelHash;
ultraChart1.Tooltips.FormatString = "<CUSTOM>";

public class MyLabelRenderer : IRenderLabel
{
 public string ToString(Hashtable context)
 {
  int row = (int)context["DATA_ROW"];
  int col = (int)context["DATA_COLUMN"];
  string customLabel = "i am a tooltip";
  //use row and col to fetch an item from your dataset
  //customLabel = GetMyValueFromDataSet;
  return customLabel;
 }
}

Max this does not work with composite charts. Can you help?

Your only option is to use IRenderLabel to implement this.

private void Form1_Load(object sender, EventArgs e)
{
   Hashtable labelHash = new Hashtable();
   labelHash.Add("CUSTOM", new MyLabelRenderer());
   myChart.LabelHash = labelHash; 
   myChart.Tooltips.FormatString = "<CUSTOM>";
}

Hi,

thanks for the help... But my requirement is to show tooltip data...

i.e my chart tool tip also contains the value from non visible fields....

Please help!!!!!!!!!