Android AdMob ad does not come up most of the time

I have a AdMob banndr ad on my mobile 开发者_运维技巧app. Most of the time it does not come up. Is this the way it works, or did I do something wrong in setting it up? Ted

If there is no ad to display then an ad is not returned. If you login to your account on admob, in the table that lists your apps there will be a fill rate percentage. That shows what percentage or your requests return ads.

Accept answers to your previous questions.