FTB 1.6.4 Modpack Crash

Logging in...
Beginning authlib authentication attempt
successfully created YggdrasilAuthenticationService
Login complete.
Checking local assets file, for MC version1.6.4 Please wait!
Setting up native libraries for Crash Landing v 1.1.2.1 MC 1.6.4
Syncing Assets:
Java Path: C:\Program Files\Java\jre7\bin\javaw.exe
Pack: Crash Landing 1.6.4
Setting MinMemory to 256
Setting MaxMemory to 8149
Defaulting PermSize to 256m
Oct 02, 2014 10:34:29 AM net.minecraft.launchwrapper.LogWrapper log
INFO: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Oct 02, 2014 10:34:29 AM net.minecraft.launchwrapper.LogWrapper log
SEVERE: Unable to launch
java.lang.ClassNotFoundException: cpw.mods.fml.common.launcher.FMLTweaker
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:102)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:94)
at net.minecraft.launchwrapper.Launch.main(Launch.java:27)