To use the [EventHandler] , you (the class having this tag) should be correctly hooked up with the primary EventBus in the application. Are you sure you are doing that?
In short, you need to do:
// Registers instance to the platform. Required for supporting [EventHandler].
FlexGlobals.topLevelApplication.dispatchEvent(ObjectEvent.newAddition(this));
Out of curiosity, why are you trying to handle NavigationRequest event? Any thing that does not work for you? Some special use-case?
