didFailToReceiveAdWithError not called

My application is using iAd's but ads are only shown in US, Canada, Spain and UK. In 开发者_开发问答all other countries I have requests but no impressions.

I made a custom banner image for my full version of the app that loads every time the iAd returns didFailToReceiveAdWithError. When the iAd is loading again i hide my custom ad.

In test everything is working... sometimes I see my own but most of the time I see an iAd.

When I download this app from App Store and test I never see my own ad and never see the iAd banner.

My question:

Is didFailToReceiveAdWithError only called if somethings goes wrong? Is the event called if everything works but Apple has no add to show based on my profile, country etc.?

Kind regards Michael

Make sure to set the delegate of your ad banner when the view loads, for example:

- (void)viewDidLoad
{
    [super viewDidLoad];
    ad.delegate = self;
}