SI error

21:18:36 [SEVERE] Could not pass event InventoryClickEvent to StackableItems v0.9.2
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
        at net.minecraft.server.v1_5_R1.PlayerConnection.a(PlayerConnection.java:1178)
        at net.minecraft.server.v1_5_R1.Packet102WindowClick.handle(SourceFile:31)
        at net.minecraft.server.v1_5_R1.NetworkManager.b(NetworkManager.java:292)
        at net.minecraft.server.v1_5_R1.PlayerConnection.d(PlayerConnection.java:113)
        at net.minecraft.server.v1_5_R1.ServerConnection.b(SourceFile:35)
        at net.minecraft.server.v1_5_R1.DedicatedServerConnection.b(SourceFile:30)
        at net.minecraft.server.v1_5_R1.MinecraftServer.r(MinecraftServer.java:580)
        at net.minecraft.server.v1_5_R1.DedicatedServer.r(DedicatedServer.java:225)
        at net.minecraft.server.v1_5_R1.MinecraftServer.q(MinecraftServer.java:476)
        at net.minecraft.server.v1_5_R1.MinecraftServer.run(MinecraftServer.java:409)
        at net.minecraft.server.v1_5_R1.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.NoSuchFieldError: DROPPER
        at haveric.stackableItems.SIPlayerListener.inventoryClick(SIPlayerListener.java:697)
        at sun.reflect.GeneratedMethodAccessor263.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
        ... 14 more