[flexcoders] why don't create AdvancedDataGrid in new window

[lehaianh1986]

I have a main window and want to create a new window to show result.
Result exist in the AdvancedDataGrid. I don't know although it run but
I can't see anything. Here is my code

import ...
var options:NativeWindowInitOptions = new NativeWindowInitOptions();
....
var newWindow:NativeWindow = new NativeWindow(options);         
....
var client:AdvancedDataGrid = new AdvancedDataGrid;
  client.dataProvider = DescriptionResults;
                                
  var col1:AdvancedDataGridColumn = new AdvancedDataGridColumn();
  col1.dataField = "abc";
  col1.headerText = "abc abc";

  var col2:AdvancedDataGridColumn = new AdvancedDataGridColumn();
  col2.dataField = "def";
  col2.headerText = "def def";

  client.groupedColumns = [col1, col2];
                                
  client.x = 200;
  client.y = 100;
  client.width = Capabilities.screenResolutionX - 600;
  client.height = Capabilities.screenResolutionY - 200;
  client.validateNow();

  newWindow.stage.addChild(client);
  //show the new window
  newWindow.activate();

In debug mode I am sure that client.dataProvider and
client.groupedColumns still have value. 

Anyone can help me why the AdvancedDataGrid don't visible ? 

Hai Anh