Bukkit

Hello !
I've a problem with the plugin Shop (last version for 1.7.2-R.03, see here : http://dev.bukkit.org/bukkit-plugins/shops/)
When I install the plugin, i start my server without problems. Me and my friends create Shops, everything goes well, we have ~15 shops.
I restart my server and I have not installed or changed anything, and surprise ! Errors logs, shops destroyed (sign become empty, juste
one shop was not affected). Errors logs :
[23:58:27] [Server thread/INFO]: [Shop] Enabling Shop v1.4.8
[23:58:27] [Server thread/INFO]: [Shop] Shops will use emerald as the currency on the server.
[23:58:28] [Server thread/ERROR]: Error occurred while enabling Shop v1.4.8 (Is it up to date?)
java.lang.NullPointerException
    at org.bukkit.craftbukkit.v1_7_R1.block.CraftSign.<init>(CraftSign.java:17) ~[craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.craftbukkit.v1_7_R1.block.CraftBlock.getState(CraftBlock.java:252) ~[craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at com.snowgears.shop.ShopHandler.loadShopsFromConfig(ShopHandler.java:211) ~[?:?]
    at com.snowgears.shop.ShopHandler.loadShops(ShopHandler.java:195) ~[?:?]
    at com.snowgears.shop.Shop.onEnable(Shop.java:147) ~[?:?]
    at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:250) ~[craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:350) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:389) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.craftbukkit.v1_7_R1.CraftServer.loadPlugin(CraftServer.java:439) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at org.bukkit.craftbukkit.v1_7_R1.CraftServer.enablePlugins(CraftServer.java:375) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.MinecraftServer.m(MinecraftServer.java:342) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.MinecraftServer.g(MinecraftServer.java:319) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.MinecraftServer.a(MinecraftServer.java:275) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.DedicatedServer.init(DedicatedServer.java:175) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:424) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
    at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617) [craftbukkit-1.7.2-R0.3.jar:git-Bukkit-1.7.2-R0.3-b3020jnks]
[23:58:28] [Server thread/INFO]: [iDisguise] Enabling iDisguise v3.0.3

The file that contains shops kept only one store, others have disappeared. In my server, i've installed : Orebfuscator, BetterReload, WorldEdit, NoCheatPlus, Vault, Multiverse-Core, PermissionsEx, Vote, MyCommand, Prism, WorldGuard, dynmap, AutoMessage, iConomy, BasicMaintenance, Shop, iDisguise, Lockette, Modifyworld, CleanroomGenerator, KillsPay, Essentials, EssentialsSpawn, Multiverse-Portals, Multiverse-Inventories, xAuth, EssentialsChat.

I need your help please !