There are a few reasons rewarded video isn't working:
1. Please make sure that you have Rewarded Video turned on for the app in your Manage Apps section.
2. We might not have any advertiser demand in your geo/app category. Please turn on the Test Toggle for the app in your Manage Apps section.
3. Our SDK must be able to access the device ID of the phone in order to serve rewarded video since we need to be able keep track of how much currency we are rewarding. Please check that your device ID is not disabled:
a. If you are on Android, make sure you have successfully integrated Google Play Services SDK. With Google's new ad policy, you must have Google Play Services SDK integrated to enable us to access the phone's ID.
b. Make sure you do not have "Opt out of interest based ads" or "Limit Ad Tracking" enabled. For Android, Google Settings -> Ads -> Reset Advertising ID. For iOS, Privacy -> Advertising -> Reset Advertising Identifier.
c. If you are on Android, make sure that you are using a device that is Android 4.0+. If you are on iOS, make sure you are using iOS > 6. We cannot serve video on older OS versions due to user experience concerns.
d. Try resetting your device ID. For Android, Google Settings -> Ads -> Reset Advertising ID. For iOS, Privacy -> Advertising -> Reset Advertising Identifier.