PVZ Heroes, 4th event card glitch

I'm a newer player, and so I grinded the weekly event out to try to get all 4 cards, I did end up doing that, however I ended up with only three however I got all 4 but I can't use one of the cards. On the event tab it says I have all 4 cards, but in my collection I have 3, and it also wouldn't allow me to gain any more tickets, so now I'm confused. Can someone please help me.