iPhones and iPads do not allow Flash in their browsers. This means that any Campaign booked with only a Flash creative will not be shown.
You can however take precautionary measures for this problem by uploading a back-up image. This is a small image creative which will only be shown in case the browser does not allow Flash.
We strongly recommend that you always upload a back-up image when creating a Flash creative.
We know that in some cases the customer fails to deliver a back-up creative, which is why you have the possibility of adding a 1×1 image as the back-up, but it is when doing this that you may experience that campaigns are not shown. Because the 1×1 pixel is so small it will appear as if no advertisement is available and to make it even more problematic; when you are exposed to the 1×1 pixel image it will be registered as an impression to the campaign statistics.