Android AdMob SDK - requesting a new Advert returns same Advert

I have an AdView in the main activity with its requestInterval set to (the recommended) 20 seconds.

The problem is that the Advert never seems to change.

I know that the refreshes are occurring as I get callbacks to onReceiveRefreshedAd on the AdListener, furthermore the impressions are being counted in the Sites and Apps Reporting control panel.

I can see that the AdView flickers just after the onReceiveRefreshedAd callback occurs, so my assumption is that AdMob is simply serving the same ad time after time.

The only way to get a new/different advert is to restart the activity.

This isn't the way its supposed to behave surely?

I'm not in test mode nor am I using a registered test device.

Thanks,

It is very common to return the same ad, as well as not returning any ads at all, the ads can have a specific target applications, which are with "higher" priority, so you are getting one of the ads that doesn't require anything in particular :)

EDIT: once your app becomes more popular, it will show different ads more frequently, so don't worry about it.