energy net pitching a fit

[01:42:23] [Server thread/ERROR] [FML]: Exception caught during firing event ic2.api.energy.event.EnergyTileLoadEvent@22ea10bd:
java.lang.NoClassDefFoundError: net/minecraft/world/World$2
        at net.minecraft.world.World.func_147460_e(World.java:690) ~[ahb.class:?]
        at ic2.core.energy.EnergyNetLocal.addTileEntity(EnergyNetLocal.java:169) ~[EnergyNetLocal.class:?]
        at ic2.core.energy.EnergyNetLocal.addTileEntity(EnergyNetLocal.java:64) ~[EnergyNetLocal.class:?]
        at ic2.core.energy.EventHandler.onEnergyTileLoad(EventHandler.java:27) ~[EventHandler.class:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler_90_EventHandler_onEnergyTileLoad_EnergyTileLoadEvent.invoke(.dynamic) ~[?:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54) ~[ASMEventHandler.class:?]
        at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:139) [EventBus.class:?]
        at appeng.integration.modules.IC2.addToEnergyNet(IC2.java:58) [IC2.class:?]
        at appeng.tile.powersink.IC2.addToENet(IC2.java:86) [IC2.class:?]
        at appeng.tile.powersink.IC2.onReady(IC2.java:68) [IC2.class:?]
        at appeng.tile.grid.AENetworkPowerTile.onReady(AENetworkPowerTile.java:72) [AENetworkPowerTile.class:?]
        at appeng.hooks.TickHandler.onTick(TickHandler.java:239) [TickHandler.class:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler_409_TickHandler_onTick_TickEvent.invoke(.dynamic) [?:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54) [ASMEventHandler.class:?]
        at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:139) [EventBus.class:?]
        at cpw.mods.fml.common.FMLCommonHandler.onPostServerTick(FMLCommonHandler.java:247) [FMLCommonHandler.class:?]
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:590) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685) [li.class:?]
[01:42:23] [Server thread/ERROR] [FML]: Index: 1 Listeners:
[01:42:23] [Server thread/ERROR] [FML]: 0: NORMAL
[01:42:23] [Server thread/ERROR] [FML]: 1: ASM: ic2.core.energy.EventHandler@76d60e70 onEnergyTileLoad(Lic2/api/energy/event/EnergyTileLoadEvent;)V
[01:42:23] [Server thread/ERROR] [FML]: Exception caught during firing event cpw.mods.fml.common.gameevent.TickEvent$ServerTickEvent@32ee9d3:
java.lang.NoClassDefFoundError: net/minecraft/world/World$2
        at net.minecraft.world.World.func_147460_e(World.java:690) ~[ahb.class:?]
        at ic2.core.energy.EnergyNetLocal.addTileEntity(EnergyNetLocal.java:169) ~[EnergyNetLocal.class:?]
        at ic2.core.energy.EnergyNetLocal.addTileEntity(EnergyNetLocal.java:64) ~[EnergyNetLocal.class:?]
        at ic2.core.energy.EventHandler.onEnergyTileLoad(EventHandler.java:27) ~[EventHandler.class:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler_90_EventHandler_onEnergyTileLoad_EnergyTileLoadEvent.invoke(.dynamic) ~[?:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54) ~[ASMEventHandler.class:?]
        at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:139) [EventBus.class:?]
        at appeng.integration.modules.IC2.addToEnergyNet(IC2.java:58) ~[IC2.class:?]
        at appeng.tile.powersink.IC2.addToENet(IC2.java:86) ~[IC2.class:?]
        at appeng.tile.powersink.IC2.onReady(IC2.java:68) ~[IC2.class:?]
        at appeng.tile.grid.AENetworkPowerTile.onReady(AENetworkPowerTile.java:72) ~[AENetworkPowerTile.class:?]
        at appeng.hooks.TickHandler.onTick(TickHandler.java:239) ~[TickHandler.class:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler_409_TickHandler_onTick_TickEvent.invoke(.dynamic) ~[?:?]
        at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54) ~[ASMEventHandler.class:?]
        at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:139) [EventBus.class:?]
        at cpw.mods.fml.common.FMLCommonHandler.onPostServerTick(FMLCommonHandler.java:247) [FMLCommonHandler.class:?]
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:590) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685) [li.class:?]