Plugin Help PermissionsEX

When I start the server PEX won't enable and I get this error:

[11:27:20] [pool-4-thread-1/ERROR]: [PermissionsEx] Error occurred with PermissionsEx! Please post it to http://git.io/9qNSNw. Full error:
java.lang.NoSuchMethodError: com.google.common.cache.CacheBuilder.maximumSize(J)Lcom/google/common/cache/CacheBuilder;
at ru.tehkode.permissions.RegExpMatcher.<init>(RegExpMatcher.java:17)
at ru.tehkode.permissions.PermissionManager.<init>(PermissionManager.java:58)
at ru.tehkode.permissions.bukkit.PermissionsEx.onEnable(PermissionsEx.java:164)
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:316)
at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:324)
at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:404)
at org.bukkit.craftbukkit.v1_7_R3.CraftServer.loadPlugin(CraftServer.java:446)
at org.bukkit.craftbukkit.v1_7_R3.CraftServer.enablePlugins(CraftServer.java:380)
at net.minecraft.server.v1_7_R3.MinecraftServer.n(MinecraftServer.java:352)
at net.minecraft.server.v1_7_R3.MinecraftServer.g(MinecraftServer.java:326)
at net.minecraft.server.v1_7_R3.MinecraftServer.a(MinecraftServer.java:282)
at net.minecraft.server.v1_7_R3.DedicatedServer.init(DedicatedServer.java:182)
at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java:436)
at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:628)