why does my Mastercard not work when I'm making purchases on my phone and nowhere else?

I'm basically the only human non alien being that likes PVZ2 and i wanted to buy some gems so i could buy kiwibeast (because he's like gloom shroom and gloom shroom is REALLY good) but when i tried to buy it it didn't work because it said something along the lines of "something isn't working" (not exactly that but it was just random words I can't understand), and as much as i tried (i even used the card scanning feature) it didn't work! if someone could help it would be VERY helpful