Assassin Protection Decoy - bugged against Zakhan?

[Erza Scarlet]

So we tried it many times, but instead of the pt going into stealth -> pt gets ''resistance'' message instead of the pt going into stealth.. can any pro sin give advice? we are struggling atm since we dont have a summoner. (its the aoe after someone gets ''marked'' and ppl need to ''stack'' into the aoe.