Epic Cards Battle

Why i cannot log in , when i open this game , and automaticly out . I use ipad , it's happen when i want buy cash and still loading then out from the game

Why i cannot log in , when i open this game , and automaticly out . I use ipad , it's happen when i want buy cash and still loading then out from the game , pls help , i already bought it , i want to play this game