Show and hide iad

This code was rejected .It had something to do with hide and show iad didnt seem to hide when theres no iad so whats do i need to change?

var adMobModule = require('ti.admob');

var userAdView = Ti.UI.createView({ height: Ti.UI.SIZE,//dp(50), bottom: 0, backgroundColor: '#000' }); win.add(userAdView);

var iAdView = Ti.UI.iOS.createAdView({ bottom: -50 });

iAdView.addEventListener('load', function(e){ iAdView.bottom = 0;

});

iAdView.addEventListener('error', function(e){ //hide iad? iAdView.bottom = -50;

});

userAdView.add(iAdView);