Thanks David for your reply but I have solved it in my own way.

As David has said the datas are not passed from the client side to the server side but you can track the event at the client side itself I mean u can use javascript for tracking the events. This is how I have solved this.

Add the below written tag inside the opening and closing of the "'igchart:UltraChart" tag

<ClientSideEvents ClientOnMouseClick="UltraChart1_ClientOnMouseClick" />

This will call the javascript function

function UltraChart1_ClientOnMouseClick(this_ref, row, column, value, row_label, column_label, evt_type, layer_id)

Here also if you look the "row" will be 0 but the "layer_id" will be different. At the server side "layer_id" will be giving only the layer_id but at client side "layer_id" will be  "layer_id-0", "layer_id-1", "layer_id-2" and so on. This 0,1,2 is our row id. Now its simple use the split function to split the string and save it inside a hidden field like below.

var rowId = layer_id.toString().split('-');
document.getElementById('hdnText').value = rowId[1]; // 'hdnText' is the id of a hidden field

Dont forget to add OnChartDataClicked="UltraChart1_ChartDataClicked" as a attribute to the
<igchart:UltraChart>

On returning it will be entrying this function

protected void UltraChart1_ChartDataClicked(object sender, ChartDataEventArgs e)

inside this function as I said in my second post start from GanttSeries and find which GanttItem like below

GanttItem ganttItem = ganttSeries.Items[e.DataColumn];

then from this GanttItem find the GanttTimeEntry like below

GanttTimeEntry ganttTimeEntry = ganttItem.Times[int.Parse(hdnText.Value)]; // hdnText is the id of the hidden field

once you have found the ganttTimeEntry it will be really really simple to find the start date and end date like below or any other data

DateTime startDate = ganttTimeEntry.Start;

DateTime endDate = ganttTimeEntry.End;

Isnt this a great solution? This solution may not be correct way to do in software development but when there is no other way to satisfy our clients we have do anything and everything.

By the way,  to add the event, I did the following

In the load event for the page I added

Dim sb As StringBuilder = New StringBuilder

sb.Append("<script>")

sb.Append(

"function OnChartMouseClick(this_ref, row, column, value, row_label, column_label, evt_type, layer_id){alert(column);}")

sb.Append(

"</script>")

Dim cstype As Type = Me.[GetType]()

"OnChartMouseClick"

, sb.ToString)

 First I put this in a IF NOTPOSTBACK block but found it would work unless on ever postback so I the script outside the if block

Also added this to the load event for the chart - added lines for chart colors since this took forever to find too.

Import system.drawing   

import system.text

.Maroon}

UltraChart1.ColorModel.CustomPalette = colors

"OnChartMouseClick"