Note that you need to bind the control after each operation that the control perform. For this purpose, we recommend to use NeedDataSource event handler
which will fire automatically when the control needs to be bound. Nevertheless, if you retrieve the data from a web service you can store the data locally, for instance in a Session and use the stored data to populate the control.
If you still experience some issues I would appreciate if you can share your code declaration and the related code behind in order to better understand your scenario.
Do you need help with upgrading your ASP.NET AJAX, WPF or WinForms projects? Check the Telerik API Analyzer
and share your thoughts.