App crash with Admob Banner

My app crash with Admob GADRequest. I tried reinstall Admob, check the app ID and ad unit ID but no help. When I deleted this line

bannerView.load(GADRequest)

The app not crash anymore but I can't show ad. It crash on this line

class AppDelegate: UIResponder, UIApplicationDelegate{

Terminating app due to uncaught exception: ""NSInvalidArgumentExceptionThe code to show ad:

bannerView.adUnitID = "ca-app-pub-3940256099942544/2934735716"/ 
        bannerView.delegate = self                                  
        bannerView.rootViewController = self 

        let requestAd: GADRequest = GADRequest() 
        requestAd.testDevices = [kGADSimulatorID] 
        bannerView.load(requestAd)