Admob works doesn't gives me money

AdMob works even if it's not published on the Market. Probably you're getting no money because nobody clicked on your banner; check in the report page on AdMob's site how many clicks you received. And keep in mind that most of the times a click is counted only if the advertiser page is fully loaded and that AdSense banners (if you've activated them) have a 48 hours delay.

You can't expect money at 30 impressions. Self-clicks don't count and if you click more often, you will get banned. Maybe around 500 impressions the first money will come. Check that you enabled google ads for better fill rate-

Just wait and make another app. I hated the time until my apps became popular but I used it to make more apps. Now 2 of my apps are well-known and I can almost live from this money. Be creative.

Well, simple answer: No one has clicked on the banner. There may be 30 times that a banner has been requested (User opens the activity and admob tries to load a banner) but non of the Users has clicked on it.