I was able to resolve my issues by setting ajaxEnabled to false.

Thank you

I am adding this in the rowIslandsPouplating mehod but I get a script error when the child grid expand.  Runtime Exception: TypeError: $IG[objName] is not a function

My code:

var child = new ContainerGrid();

e.Row.RowIslands.Add(child);

var selection = new RowSelectors

{

Enabled = true,

RowNumbering = false,

RowSelectorCssClass = "selector",

HeaderRowSelectorCssClass = "HeaderRowSelector"

};

child.Behaviors.Add(selection);

selection.RowSelectorClientEvents.RowSelectorClicked = "whdg1_RowSelector_RowSelectorClicked";

child.DataSource = dt;

child.DataBind();

Updating Main Grid.
Maya, I looked at you sample and it does updates the main grid value as expected.
But my scenario is different. I have problem updating main grid right after changes done to child grid in RowUpdating event.  If event triggered by main grid then it is not a problem e.g.      
after line  mr.Amount = 95000;   executed I can see changes on the main grid, if I try to do the same in the child grid section of the same event it’s not working even if I DataBind main grid again. This is the place where   mr.Amount = 35000; got executed.
The issue that I do not know how to address is the following : MainGris get binded on the PageLoad that executed before RowUpdating event, so when value in the master source changed ( mr.Amount = 35000) it could be seen only on the next postback (after any other child grid get expanded).
So somehow if the change occured in main grid and new value assign to underline source (mr.Amount = 95000) then changes can be seen, if event triggered by child grid then changes to main grid ( mr.Amount = 35000) can be seen only after another postback. Can you advise  how to make mr.Amount = 35000 visible without postback.
Project attached
Thanks.