missing forestry class?

[22:02:11] [Server thread/ERROR]: Encountered an unexpected exception
java.lang.NoSuchFieldError: generatorFuel
        at forestry.Forestry.<init>(Forestry.java:72) ~[Forestry.class:?]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_05]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[?:1.8.0_05]
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.8.0_05]
        at java.lang.reflect.Constructor.newInstance(Constructor.java:408) ~[?:1.8.0_05]
        at java.lang.Class.newInstance(Class.java:433) ~[?:1.8.0_05]
        at cpw.mods.fml.common.ILanguageAdapter$JavaAdapter.getNewInstance(ILanguageAdapter.java:173) ~[ILanguageAdapter$JavaAdapter.class:?]
        at cpw.mods.fml.common.FMLModContainer.constructMod(FMLModContainer.java:486) ~[FMLModContainer.class:?]
        at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_05]
        at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0_05]
        at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74) ~[minecraft_server.1.7.10.jar:?]
        at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47) ~[minecraft_server.1.7.10.jar:?]
        at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322) ~[minecraft_server.1.7.10.jar:?]
        at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304) ~[minecraft_server.1.7.10.jar:?]
        at com.google.common.eventbus.EventBus.post(EventBus.java:275) ~[minecraft_server.1.7.10.jar:?]
        at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:208) ~[LoadController.class:?]
        at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:187) ~[LoadController.class:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_05]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_05]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_05]
        at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0_05]
        at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74) ~[minecraft_server.1.7.10.jar:?]
        at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47) ~[minecraft_server.1.7.10.jar:?]
        at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322) ~[minecraft_server.1.7.10.jar:?]
        at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304) ~[minecraft_server.1.7.10.jar:?]
        at com.google.common.eventbus.EventBus.post(EventBus.java:275) ~[minecraft_server.1.7.10.jar:?]
        at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:118) ~[LoadController.class:?]
        at cpw.mods.fml.common.Loader.loadMods(Loader.java:492) ~[Loader.class:?]
        at cpw.mods.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:87) ~[FMLServerHandler.class:?]
        at cpw.mods.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:314) ~[FMLCommonHandler.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:117) ~[lt.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:387) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685) [li.class:?]