TreeGrid with empty folders when getting data from DataSource

[Driftdone]

Hello all,

While using SmartGWT 2.2.0 I'm trying to implement a TreeGrid, which takes data from DataSource and has the possibility to reparent itself, and add nodes even to leaves.

Can you help me with a way of doing that?

Here is my code

                final TreeGrid groupStructureTree = new TreeGrid();
		
		groupStructureTree.setCanEdit(true);
		groupStructureTree.setLoadDataOnDemand(false);
		groupStructureTree.setWidth(500);
		groupStructureTree.setHeight(400);
		groupStructureTree.setDataSource(dataSource);
		groupStructureTree.setAutoFetchData(true);
		groupStructureTree.setFolderIcon("icons/person.png");
		groupStructureTree.setNodeIcon("icons/person.png");
		groupStructureTree.setClosedIconSuffix("");
		groupStructureTree.setShowOpenIcons(false);
		groupStructureTree.setCanReorderFields(false);
		groupStructureTree.setCanReparentNodes(true);
		groupStructureTree.setCanDropOnLeaves(true);

		TreeGridField parentName = new TreeGridField("g2g_id", "Name1");
	        parentName.setOptionDataSource(DataSource.get("listing_groups"));
		parentName.setDisplayField("group_name");
		parentName.setValueField("group_id");
		

		groupStructureTree.setFields(parentName);

and my datasource

<DataSource ID="g2g" serverType="sql" tableName="g2g">
	<fields>
		<field name="g2g_id" type="integer" hidden="true" primaryKey="true" />
		<field name="g2g_record_group_id" type="integer" />
		<field name="g2g_parent_group_id" 
			   type="integer" 
			   foreignKey="g2g.g2g_id"  
			   rootValue="1"/>
	</fields>
	<operationBindings>
		<operationBinding operationType="fetch">
			<tableClause>g2g</tableClause>
			<whereClause>($defaultWhereClause)</whereClause>
		</operationBinding>
	</operationBindings>
</DataSource>

Thank you in advance,
Angel