02:17:15 [SEVERE] Could not pass event InventoryClickEvent to RealisticBackpacks v1.5
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:30)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:478)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:463)
        at net.minecraft.server.v1_6_R3.PlayerConnection.a(PlayerConnection.java:1411)
        at net.minecraft.server.v1_6_R3.Packet102WindowClick.handle(SourceFile:31)
        at org.spigotmc.netty.NettyNetworkManager.b(NettyNetworkManager.java:230)
        at net.minecraft.server.v1_6_R3.PlayerConnection.e(PlayerConnection.java:117)
        at net.minecraft.server.v1_6_R3.ServerConnection.b(SourceFile:37)
        at org.spigotmc.netty.NettyServerConnection.b(NettyServerConnection.java:132)
        at net.minecraft.server.v1_6_R3.MinecraftServer.t(MinecraftServer.java:594)
        at net.minecraft.server.v1_6_R3.DedicatedServer.t(DedicatedServer.java:240)
        at net.minecraft.server.v1_6_R3.MinecraftServer.s(MinecraftServer.java:483)
        at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:415)
        at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
Caused by: java.lang.NumberFormatException: For input string: "smallbackpack"
        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
        at java.lang.Integer.parseInt(Integer.java:492)
        at java.lang.Integer.parseInt(Integer.java:527)
        at org.fatecrafters.plugins.util.RBUtil.getItemstackFromString(RBUtil.java:51)
        at org.fatecrafters.plugins.listeners.InventoryListener.onInventoryClick(InventoryListener.java:143)
        at sun.reflect.GeneratedMethodAccessor85.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
        ... 15 more
02:17:15 [SEVERE] Could not pass event InventoryClickEvent to RealisticBackpacks v1.5
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:30)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:478)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:463)
        at net.minecraft.server.v1_6_R3.PlayerConnection.a(PlayerConnection.java:1411)
        at net.minecraft.server.v1_6_R3.Packet102WindowClick.handle(SourceFile:31)
        at org.spigotmc.netty.NettyNetworkManager.b(NettyNetworkManager.java:230)
        at net.minecraft.server.v1_6_R3.PlayerConnection.e(PlayerConnection.java:117)
        at net.minecraft.server.v1_6_R3.ServerConnection.b(SourceFile:37)
        at org.spigotmc.netty.NettyServerConnection.b(NettyServerConnection.java:132)
        at net.minecraft.server.v1_6_R3.MinecraftServer.t(MinecraftServer.java:594)
        at net.minecraft.server.v1_6_R3.DedicatedServer.t(DedicatedServer.java:240)
        at net.minecraft.server.v1_6_R3.MinecraftServer.s(MinecraftServer.java:483)
        at net.minecraft.server.v1_6_R3.MinecraftServer.run(MinecraftServer.java:415)
        at net.minecraft.server.v1_6_R3.ThreadServerApplication.run(SourceFile:583)
Caused by: java.lang.NumberFormatException: For input string: "smallbackpack"
        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
        at java.lang.Integer.parseInt(Integer.java:492)
        at java.lang.Integer.parseInt(Integer.java:527)
        at org.fatecrafters.plugins.util.RBUtil.getItemstackFromString(RBUtil.java:51)
        at org.fatecrafters.plugins.listeners.InventoryListener.onInventoryClick(InventoryListener.java:143)
        at sun.reflect.GeneratedMethodAccessor85.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
        ... 15 more