Google Play cannot verify my account when I try to buy an app on Android?

I was going to buy the Neurax worm upgrade on Plague Inc (Or any other upgrade or app), but it said "Cannot verify your account, try again later". I use Google Play for this. My phone is a T-Mobile(Samsung)Exhibit II and is Android. I tried clearing data and cache of Google Play, I tried uninstalling and re-installing, and still that error shows up. What can I do to fix this?
I have perfect Wi-Fi and it still shows up.