I'm integrating Applovin into a cocos2d-x game and interstitial ads work just fine. I'm unable to receive any banners (most likely because of my location), though.
I went through the Applovin docs and found this:
This error means “no fill” or that our server is unable to return an ad given the parameters/circumstancs of the ad request. We will never have 100% fill so it is important you can manage this error code correctly (see Best Practices for Handling 204s). If you are testing your app and need to see an ad to verify your integration, here are the likely causes of a 204 and their respective fixes:
- Advertiser demand is limited for your country/geo, app category, or phone characteristics. Fix: use the Test Toggle in the UI.
- ...
Source: http://support.applovin.com/support/solutions/articles/1000119815--define-kalerrorcodenofill-204
I suppose after enabling the test mode, that I should be able to receive test ads but I'm still getting 204s.
Once you turn on test mode it can take ~30 minutes to become effective, so you might just need to wait a bit. Also, it turns itself off after some amount of time (I think a few hours), so that could be the cause, too.