Bug on TreeView

Hi
I have a TreeView with nodes builded with
ExpandeMode = ServerSideCallback

also the treeView alows Drag And Drop

the bug accurs when I drop a node into another node which is not populated yet then I try to expand another node to populate its sub nodes!

On debuging I cant go to the function :
protected void TreeView1_NodeExpanded(object sender, Syncfusion.Web.UI.WebControls.Tools.TreeViewNodeEventArgs e)

How that happen ? is it a way to resolve that ?

Sorry for my english !! :D
Thanks !!

Sorry !!

the bug happens because on the "_TRV_NodeExpanded" function I do :
e.Node.Items.Clear();
then
I load the child nodes from Data Base!!

on Drag And Drop with expand it happen
we have to check the node if exist in child nodes before adding the childs nodes from loaded from DB.

thanks