iAd banner at Bottom of app

[AyClass]

ok so im currently in the process of adding iAd to my app for the first time, the add displays fine but it when my app runs without internet connection instead of the ad going away there is just a white box where the test ad once was.

what dimensions do i have to insert to make it go away at the bottom of the app?? is the bottom -50?

-(void)bannerViewDidLoadAd:(ADBannerView *)abanner {
    if (!self.bannerIsVisible) {
        [UIView beginAnimations:@"animatedAdBannerOn" context:NULL];
        banner.frame = CGRectOffset(banner.frame, 0, -50);
        [UIView commitAnimations];
        self.bannerIsVisible = YES;
    }
}

-(void)bannerView:(ADBannerView *) abanner didFailToReceiveAdWithError:(NSError *)error {
    
    if (self.bannerIsVisible) {
        [UIView beginAnimations:@"animatedAdBannerOff" context:NULL];
        banner.frame = CGRectOffset(banner.frame, 0, 50);
        [UIView commitAnimations];
        self.bannerIsVisible = NO;
    }
}

thanks in advance

[AyClass]

anybodyy???