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

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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.