villager and minecarts

ok well i created my zombie xp grinder like i usally do but i put a spechel piston to let the villager zombies through. when im done getting leveled i go down and cure the villagers then i put 1 in a minecart and try to send them to a village i made for them and everything works till i break the minecart to relese them, i dont know what happened but they blink out and i dont know where they go they just vanish. please help