Estou com um probleminha com as extensão do admob o app não abre quando colocar a extensão

MIT App Inventor Help
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3
  1. Contact the extension developer.
  2. Name the extension and as @ChrisWard said, the version number.
  3. Write in English, especially the topic heading.
  4. Show your relevant blocks.
  5. Name the Android version of your test device.

See also: How to ask a question (open new topic)