why in-app purchase doesn't connect in flutter

Question

I would like to implement in-app purchases in flutter using the flutter_inapp_purchase library.

I added product to in-app purchase section from apple console and product shows "ready to submit". But in-app purchase doesn't fetch products even it doesn't listen to connect.

var result = await FlutterInappPurchase.instance.initialize();
    print('result: $result');


    _conectionSubscription = FlutterInappPurchase.connectionUpdated.listen((connected) {
      print('connected: $connected');
    });

The "result" variable returns true but FlutterInappPurchase doesn't print "connected"