My normals users can't stack fence with 1.7.3 client version

Hi,
i use CB build 977 with permission 3.1.6 et essential 2.4
and this plugins :
WaterproofRedstone, ClothCommand, ControllerBlock, BorderGuard, BukkitPiston, BlocksOnGlass, xAuth, PorteCoulissante, Permissions, RetractableBridge, AutoMessage, PailStone, TimeFold, Superpickaxe, VanishNoPickup, Essentials, Whitelist, EssentialsSpawn, EssentialsGeoIP, EssentialsChat, EssentialsProtect, Minecart Mania, iZone, Giant Trees, MobArena, Dynmap.

My players can't stack fence, i don't know why, this is a native function since 1.7, it don't need a specific permission ! :|

Normals users can't with the 1.7.3 client BUT admins with '*' in permission setting CAN stack fence >.<

i past my groups.yml http://pastebin.com/70rVx3Ny normals users are called "Habitant"

thanks for any help

SOLVED