If you have already made purchases in the game or in other apps, the possible reasons may include:

1. Poor internet connection: you must have a stable connection to make purchases. It is recommended that you use either Wi-Fi or 3G/4G.
2. Errors in the app store: All purchases are processed via the store from which you downloaded the game. If the store is overloaded, there may be problems processing your request. Please wait a few minutes and try again.
3. Errors in the store app on your device, in which case the problem can be solved by rebooting your device.

If you have not previously made purchases in the game or in other apps:
1. A mistake with payment details: Try deleting your payment details and entering them again.
2. Your payment method is not supported: It is possible that the payment method you have chosen is not supported by the store. The list of supported payment methods can be viewed on the relevant customer support pages for Apple and Google.

If you still cannot complete your purchase, we recommend that you contact your app store's support service.