This event is fired when API.attachFlashAd has attached an ad to a movieclip. This does not report that the ad was loaded, merely that it has been attached.
APIEvent
This event will be an instance of APIEvent, and contain the following values:
type:String - APIEvent.AD_ATTACHED
success:Boolean - True if the ad was attached succesfully
target:MovieClip - The movieclip the ad was attached to