Hi dudes, i'm starting to implement AdWhirl in my application. i follow the instructions which is belong to adwhirl but i cant see any ad in my application.i add the following methods in my viewcontroller class

- (void)viewDidLoad {
    [super viewDidLoad];
 AdWhirlView *adView=[AdWhirlView requestAdWhirlViewWithDelegate:self];
 [self.view addSubview:adView];
}

-(NSString *) adWhirlApplicationKey{
 return @"myAdWhirlKey";
}

-(UIViewController *) viewControllerForPresentingModalView{
 return self;
}

i doesn't display anything. please help how to implement AdWhirl