Hey, here are a few reasons why the referral links may not have worked: 

There are three main reasons why players may have problems with their referral links:

1. The player that has accepted the invitation link and followed it to install the game has internal anonymizer activated for his/her phone, so we cannot identify the device for connecting it in the system. Also, the issue may be that there are emulators involved (they too, are problematic referral-wise).

2. The game has already been installed on this phone previously.

3. The user is not new (he/she may have logged in on the new device that had not had the game installed on it before, but with the account that had already been registered before).

Regarding the first point, we can suggest resetting advertising IDs or activating them to make sure that you are visible (to put it in simpler words, make sure that the device is not hidden, this can be checked in settings)