shielderror

[09:21:18 ERROR]: Could not pass event PlayerInteractEvent to Shield v2.5
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:427) ~[spigot.jar:git-Spigot-1239]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[spigot.jar:git-Spigot-1239]
        at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredLi
stener.java:30) ~[spigot.jar:git-Spigot-1239]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:482) [spigot.jar:git-Spigot-1239]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:467) [spigot.jar:git-Spigot-1239]
        at org.bukkit.craftbukkit.v1_7_R1.event.CraftEventFactory.callPlayerInte
ractEvent(CraftEventFactory.java:208) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.PlayerInteractManager.dig(PlayerInteract
Manager.java:103) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.PlayerConnection.a(PlayerConnection.java
:536) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.PacketPlayInBlockDig.a(SourceFile:53) [s
pigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.PacketPlayInBlockDig.handle(SourceFile:8
) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.NetworkManager.a(NetworkManager.java:147
) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.ServerConnection.c(SourceFile:134) [spig
ot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:6
78) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:2
73) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:5
40) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java
:446) [spigot.jar:git-Spigot-1239]
        at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:6
17) [spigot.jar:git-Spigot-1239]
Caused by: java.lang.NullPointerException
        at com.hotmail.ooosssososos.Shield.onClick(Shield.java:168) ~[?:?]
        at sun.reflect.GeneratedMethodAccessor406.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.7.0_10]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_10]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:425) ~[spigot.jar:git-Spigot-1239]
        ... 16 more