Gets or sets the owning object type and routed event name that will activate a trigger. Only the Loaded event is supported.
The only event that you can use for an EventTrigger in Silverlight is the Loaded event.
For animations that are intended to trigger from events other than Loaded, create a conventional event handler, which can be referenced either in XAML attribute syntax or by adding it with AddEventListener. From the event handler code, get a reference to a Storyboard (typically these are stored as Resources), and then call the Begin method on that Storyboard.