Unable to make 'In App purchases' for Games

I have downloaded a few great games that I enjoy playing, BUT I cannot connect to make in app purchases that are necessary to keep playing. This happens “frequently” and I can’t continue playing. Very frustrating! I get so frustrated that I end up deleting the app. I have not had this problem in the past. There is money in my account so this is not the issue. How can I fix this? Or, am I missing something?.

[Re-Titled by Moderator]