B4J Question TreeTableView drag & drop

Sub DestView_DragDropped(e As DragEvent)
    If e.GetDataIds(0) = "DTSource" Then ' it's from this program
        Dim source_ob As Object
        Dim dest_ob As Object
        Dim tti As TreeTableItem
        Dim col As Int = 3
        Log("DragDropped : DataId " & e.GetDataIds(0) & " is to be dropped")
        source_ob = e.GetDataObjectForId("DTSource")
        dest_ob = e.GetGestureTarget

        tti = dest_ob
        'tti.SetValue(col, source_ob )
        
        e.SetDropCompleted(True)
        Return
    End If
    
End Sub

SelectedItem.SetValue(1, "Sdfsdf")

Sub Process_Globals
Private DragDrop As DragAndDrop
Private SourceFields As TableView
Private DestView As TreeTableView
Private DestItem As TreeTableItem
End Sub

Sub AppStart (Form1 As Form, Args() As String)
      DragDrop.MakeDragSource(SourceFields, "SourceFields")
    DragDrop.MakeDragTarget(DestView, "DestView")
...
End Sub