new error

---- Minecraft Crash Report ----
// My bad.

Time: 29/11/13 7:06 PM
Description: There was a severe problem during mod loading that has caused the game to fail

cpw.mods.fml.common.LoaderException: java.lang.NoSuchFieldError: B
	at cpw.mods.fml.common.LoadController.transition(LoadController.java:156)
	at cpw.mods.fml.common.Loader.initializeMods(Loader.java:700)
	at cpw.mods.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:249)
	at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:509)
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:808)
	at net.minecraft.client.main.Main.main(SourceFile:101)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:27)
Caused by: java.lang.NoSuchFieldError: B
	at tutorial.basic.Basic.load(Basic.java:36)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:545)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
	at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
	at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
	at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
	at com.google.common.eventbus.EventBus.post(EventBus.java:267)
	at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:201)
	at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:181)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
	at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
	at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
	at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
	at com.google.common.eventbus.EventBus.post(EventBus.java:267)
	at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:112)
	at cpw.mods.fml.common.Loader.initializeMods(Loader.java:699)
	... 10 more


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Windows 8 (amd64) version 6.2
	Java Version: 1.7.0_45, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 211764776 bytes (201 MB) / 368574464 bytes (351 MB) up to 954728448 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Suspicious classes: FML and Forge are installed
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	FML: MCP v8.11 FML v6.4.45.952 Minecraft Forge 9.11.1.952 Optifine OptiFine_1.6.4_HD_U_C6 7 mods loaded, 7 mods active
	mcp{8.09} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized
	FML{6.4.45.952} [Forge Mod Loader] (minecraftforge-9.11.1.952.jar) Unloaded->Constructed->Pre-initialized->Initialized
	Forge{9.11.1.952} [Minecraft Forge] (minecraftforge-9.11.1.952.jar) Unloaded->Constructed->Pre-initialized->Initialized
	Backpack{1.18.17} [Backpack] (backpack-1.18.17-1.6.2.zip) Unloaded->Constructed->Pre-initialized->Initialized
	tutorial{0.0.1} [Tutorial] (basic.zip) Unloaded->Constructed->Pre-initialized->Errored
	ComputerCraft{1.57} [ComputerCraft] (ComputerCraft1.57.zip) Unloaded->Constructed->Pre-initialized->Initialized
	CCTurtle{1.57} [ComputerCraft Turtles] (ComputerCraft1.57.zip) Unloaded->Constructed->Pre-initialized->Initialized