Unity Ads doesn't show any ads when using real id in Android Java

I have a hard time figuring out how to correctly implement Unity Ads. At first, I use test id to test the ads and it works well. But when I switch to my own gameId, there’s no ads to show. I’ve published the app to Google Play and in my Unity Dashboard, it tells me that it has Ad Request but no impression. Then I try to debug it, I get D/unity banner: Placement banner could not be found in the log. I wonder what did I do wrong.

Many thanks to everyone who help this!

Hi willedward,

May you provide us more details about your project, such as sample codes or full device logs? From your question, it seems that you are using a wrong placementId. May you check it from the Unity Dashboard?