AuthMe 2.7.9b4 spout error

java.lang.NoClassDefFoundError: org/getspout/spoutapi/gui/PopupScreen
        at uk.org.whoami.authme.AuthMe.onEnable(AuthMe.java:237)
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:217)
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:457)
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:381)
        at org.bukkit.craftbukkit.v1_4_R1.CraftServer.loadPlugin(CraftServer.java:282)
        at org.bukkit.craftbukkit.v1_4_R1.CraftServer.enablePlugins(CraftServer.java:264)
        at net.minecraft.server.v1_4_R1.MinecraftServer.j(MinecraftServer.java:321)
        at net.minecraft.server.v1_4_R1.MinecraftServer.e(MinecraftServer.java:300)
        at net.minecraft.server.v1_4_R1.MinecraftServer.a(MinecraftServer.java:259)
        at net.minecraft.server.v1_4_R1.DedicatedServer.init(DedicatedServer.java:149)
        at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:399)
        at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)
Caused by: java.lang.ClassNotFoundException: org.getspout.spoutapi.gui.PopupScreen
        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 org.bukkit.plugin.java.PluginClassLoader.findClass0(PluginClassLoader.java:80)
        at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:53)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        ... 12 more