There may be one or more of the following reasons for this :-
- Conversion rate is too low which indicates some technical issue with your app or tracking.
- We are sending traffic but NOT getting any Conversion postback from your external / 3rd party tracking.
- Your app is unavailable or NOT listed in google play / app store any more.
- Your app is capatible with limited devices and hence significant users are NOT able to install it.
- High risk of fraud has been detected.