Установите Radgrid DataSource Clientside

//need to clear first the rad client datasource before fetching updated data
$find("<%=radClientDatasourceID=%>").set_data("");
$find("<%=radClientDatasourceID=%>").fetch(function(args){

$find("<%=radgrid=%>").get_masterTableView().set_dataSource(args.get_data);
$find("<%=radgrid=%>").get_masterTableView().dataBind();
});
Fantastic Flatworm