show all child nod data based on parent node selection Rad Drop Down Tree

Hi,
I am new to rad dropdown tree. I want to show data from database based on selection in Rad dropdown tree. 
All I want that when a child node is selected it should show data based on that node selection (This scenario is working fine) butwhen a parent node is selected it is not showing data based on all its child nodes.

Please note that each item in Rad Drop Down Tree have a unique product_type_id  and on bases of product_type_id  I am executing query to show result.


Thanks