I especially created a PayPal account to be able to buy crystal. Since the activation of my PayPal account I also received a double crystal card which I also couldn’t use due to the same error as that of SilentDeath. The past few weeks I have tried many times to buy some crystals to upgrade my tanks and weapons. If this problems continues I might change my mind and earn the needed crystals during the battles instead of buying. It’s much cheaper too! regards, Mouse4kill