We cannot be sure what exactly is going wrong. The dataSource is configured for JSONP but from the response it's not getting clear if you are actually returning JSON or JSONP.
Please provide more information about what data you are returning from your DataService or prepare example where the issue is reproduced - hopefully this will help us pinpoint the exact reason for this behaviour.
the Telerik team
Join us on our journey to create the world's most complete HTML 5 UI Framework - download Kendo UI