This always happens to me in PvP and also in PvE to a certain extent. All the other skills seems to work fine but this one seems to fail more then occasionally. I am wondering if others have experienced the same. I keep tapping the button but it won't fire. I have tapped about a dozen times, placing my thumb on the button for several seconds and it just won't fire. I don't think it is a ping issue and my hands/iPhone Screen are clean so it is not a contact issue either.