There might be a couple of reasons why you might be having problems.

If you have previously made purchases please check the following:

1. You will need a stable internet connection It has to be stable in order to make purchases, so we recommend using Wi-Fi or at least a 3G/4G connection while making purchases.
2. Temporary problems with the app store. All in-game purchases are processed by the store where the game was downloaded from. There might a chance that the store is unable to process your request at the time you are making the request. In that case, just wait several minutes and try again.
3. Problems with the store app. These are usually solved by restarting your device.

If you have never made purchases before in the game or other with other applications please check:

1. Make sure your payment information is correct. If you made a mistake while entering your payment information, cancel the payment and start over.
2. Unsupported payment method. It might be that the payment method you want to use is not supported by the app store. You can check a list of available payment methods on the Apple and Google Customer Support websites.

If you still have problems making purchases, please contact the app store customer support.