How to show ads in facebook Instant Game?

Question

This is my code:

FBInstant.getInterstitialAdAsync('111_222')
    .then(function (interstitial){
        if(typeof interstitial !== 'undefined'){
            if (typeof interstitial.getPlacementID() === 'undefined'){
                this.setState({adId: 'can not get  placement ID'})
            }
            preloadedInterstitial = interstitial;
            return preloadedInterstitial.loadAsync()
        }else{
            return Promise.reject(new Error('interstitial is undefined'))
        }
    })
    .then(function(){
        this.setState({ad: 'adv loaded'})
    })
    .catch(function(error){
        this.setState({adId: error.code + error.message})
})

I can't see anything in messenger, and my app is still in test version.

oh，I get it，I made a common-sense mistake.