iAds ADBanner disappear when back button is clicked

i have a navigation controller with a depth of 3 viewcontro开发者_StackOverflowllers. root, one, two i want to add an ADBannerview and I followed the iAdsSuite sample code from apple. i added to all of my viewcontrollers. the adbanner loads at first then it is fine if i navigate to one and two. but if i click back button from two and one, the banner is not loading anymore. it is working root --> one --> two but it's not working two --> one --> root. anyone encounter this problem?

It's impossible to diagnose the problem without looking at the source, however this sounds like a memory management issue to me. Something might be getting released when it shouldn't, or perhaps isn't being retained.

I endup implementing ADBannerView in appDelegate. Use custom delegate method to resize the UITableview of one and two. Don't know it is the right way to do...