krull skin not aquired after buy

i bought the krull skin for my son, i bought so i hade 200 dragon teeth i pressed they buy button for the krull skin and then it poped up a window with a 4box item couse my son dident have space in the bank,then we made space in the bank and we double tapped the item so that it would go into the bank, but it did not go into the bank it just disapeared?