i erase all, and i did all from scrash again :
i did a fresh install of xenforo 1.5.5a
i import data from my all vbulletin 4.x (take long time but the only problem i had is for merge user with the same email)
i did a fresh install of vaultwiki 4.0.8 b3
i imported data from vaultwiki 3.x
unfortunatly i had exactly the same problem