Tree Grid Pagination Support with Smart Gwt-4.0p

Hi,
We are using SmartGWT 4.0 Library - Licensed Version.
As we required "pagination" for Tree Grid.
I have enabled the following properties for my Tree Grid,

grouptreeGrid.setDataFetchMode(FetchMode.PAGED);
grouptreeGrid.setDataPageSize(30);
grouptreeGrid.setAutoFetchData(true);

Data Source Used : "Rest Data Source"
We are sending "startIdex" and "Count" values in the Rest Request body as follows,
{
..
"startIndex":0, "count":30,
..
}
I have 50 child nodes in DB,
For the first time request is able to fetch first "30" records from the server,
But After scrolling down for the next 20 records, the request is not able to send by the "treeGrid" automatically like "List Grid".

Please let me know, Smart Gwt-4.0 is having the support or not.
If yes,
is it required any client side logic I have to added.

Please let me know your comments.

Thanks