@React-Native-firebase/admob does not work

Question

I am trying to insert ads into my code in React Native via the @React-Native-firebase/admob library. I took the whole step by step of the Admob platform to create my account and create my first project there. I also set firebase to link a firebase project to the project created in Admob.

However, when I try to compile the code with a banner ad, I get the following error:

[admob/error-code-no-fill] The ad request was successful, but no ad was returned due to lack of ad inventory.]

Obs.: I’m trying to insert a banner with the Testids, and still get this error.

Library versions in my package.json:

"@react-native-firebase/admob": "^11.2.0",
"@react-native-firebase/app": "^11.2.0",

Part of my ad code:

import { BannerAd, BannerAdSize, TestIds } from '@react-native-firebase/admob'

...

const testBannerId = TestIds.BANNER

...

<BannerAd
  unitId={testBannerId}
  size={BannerAdSize.BANNER}
  onAdClosed={() => console.log('closed')}
  onAdFailedToLoad={(error: any) => console.log(error)}
  onAdLeftApplication={() => console.log('Ad left application')}
  onAdLoaded={() => console.log('Ad loaded')}
  onAdOpened={() => console.log('Ad opened')}
/>

Does anyone have any idea what’s going on? Thank you very much!