After publishing new version of android app to google play admob status changed to inactive and no ads are displayed
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Admob was showing ads on my application, everything was working fine. Then I created a new version of that app, uploaded it to google play and ads stopped appearing. In admob the status of this app chnaged to "Inactive: AdMob has never received an ad request for your site" (the bubble got from green to red) despite the fact that there is some revenue from the first version, when the ads were still working. 

I didn't change adUnitId, it's the same like Publisher id shown in admob. When I run that app from eclipse test ads appear correctly, but only test ads. If I remove my device from list of test devices an ad is never displayed.

What could be the problem? Do I need to create a new app in admob for every app update in google play store? (which seems unlogical to me)

Thank you.