When we have templates the generation of the clientIDs is dynamical. If some controls are removed and added back to the controls collection their clientIDs are changed. We can give a reference to the control in the Add method and onprerender the ToolTipManager could find their ClientIDs.
 E.g. the following demo: http://demos.telerik.com/aspnet-ajax/orgchart/examples/applicationscenarios/integrationwithradtooltip/defaultcs.aspx. is not working when we have DrillDown.