i migrated UltraWebTree to WebDatatree and facing some java script Issues like

for UltraWebTree  

var test = parent.frames["fmNew"].igtree_getTreeById("webDataTreeNew").getNodes()[StartIndex];

was working perfect after changing to WebDatatree  its not working. giving Error: Object doesn't support property or method 'igtree_getTreeById'.

Then after goggling i replaced igtree_getTreeById("webDataTreeNew") with $util.findControl("webDataTreeNew") But still no luck.

What is the Equivalent for below line of code in WebDataTree:-

 var test = parent.frames["fmNew"].igtree_getTreeById("webDataTreeNew").getNodes()[StartIndex];

Thanks

Ravi