swift – 为什么我的facebook插页式广告不会显示在我的应用中？

我在 Swift中,每次我调用它们委托func didFailWithError被调用.我在我的所有应用程序中使用与facebook intertial广告相同的代码,除了我创建的这个新应用程序外,它完美无缺.没有广告弹出,我在控制台中收到一条消息说：

diskCookieStorage changing policy from 2 to 0,cookie file:
file:///private/var/mobile/Containers/Data/Application/4E5FA239-208C-4B08-87C6-E4DB1CC3CC76/Library/Cookies/Cookies.binarycookies

这是我在GameViewController中设置代码的方法：

import UIKit
import SpriteKit

let interstitialFBAD: FBInterstitialAd = FBInterstitialAd(placementID: "2320559454634478_1321860725967683")

class GameViewController: UIViewController,FBInterstitialAdDelegate {

override func viewDidLoad() {
    super.viewDidLoad()

    if let scene = GameScene(fileNamed:"GameScene") {

        loadFBInterstitialAd()

    }
}

//fbAds--------------------------------------------------------------------------------------------------------

func loadFBInterstitialAd() {
    interstitialFBAD.delegate = self
    interstitialFBAD.load()
    print("what")
}


func interstitialAdDidLoad(_ interstitialAd: FBInterstitialAd) {
    interstitialFBAD.show(fromrootViewController: self)
    print("popup")
}

func interstitialAd(_ interstitialAd: FBInterstitialAd,didFailWithError error: Error) {
    print("Failed")
}

//fbAds--------------------------------------------------------------------------------------------------------