     {
       _id = id;
 
-      if (!ExternalInterface.available)
+      if (!externalInterfaceIsAvailable())
       {
         raiseError("ExternalInterface unavailable");
         return;
       }
 
+      _initialized = true;
       _viewabilityCheck = new OVVCheck(_id);
 
       _intervalsInView = 0;

    private static const IMPRESSION_DELAY:Number = 250;
    private static const VIEWABLE_AREA_THRESHOLD:Number = 50;

    private var _id:String;
    private var _viewabilityCheck:OVVCheck;
    private var _impressionTimer:Timer;


    public function checkViewability():Object
    {
      if (!_initialized)
        raiseError("ExternalInterface unavailable");

      return performCheck();
    }

