Signshop SSLINK ERROR

[23:10:00] [Server thread/ERROR]: Could not pass event SSLinkEvent to SignShop v2.11.0
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:310) ~[spigot.jar:git-Spigot-db6de12-07c3001]
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-db6de12-07c3001]
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot.jar:git-Spigot-db6de12-07c3001]
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-db6de12-07c3001]
    at org.wargamer2010.signshop.SignShop.scheduleEvent(SignShop.java:192) [SignShop_v2.11.0.jar:?]
    at org.wargamer2010.signshop.util.signshopUtil.registerClickedMaterial(signshopUtil.java:451) [SignShop_v2.11.0.jar:?]
    at org.wargamer2010.signshop.util.signshopUtil.registerClickedMaterial(signshopUtil.java:438) [SignShop_v2.11.0.jar:?]
    at org.wargamer2010.signshop.util.signshopUtil.registerClickedMaterial(signshopUtil.java:433) [SignShop_v2.11.0.jar:?]
    at org.wargamer2010.signshop.listeners.SignShopPlayerListener.onPlayerInteract(SignShopPlayerListener.java:229) [SignShop_v2.11.0.jar:?]
    at sun.reflect.GeneratedMethodAccessor186.invoke(Unknown Source) ~[?:?]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_91]
    at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_91]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) [spigot.jar:git-Spigot-db6de12-07c3001]
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [spigot.jar:git-Spigot-db6de12-07c3001]
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot.jar:git-Spigot-db6de12-07c3001]
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-db6de12-07c3001]
    at org.bukkit.craftbukkit.v1_8_R3.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:228) [spigot.jar:git-Spigot-db6de12-07c3001]
    at org.bukkit.craftbukkit.v1_8_R3.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:195) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.PlayerInteractManager.a(PlayerInteractManager.java:107) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:623) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.PacketPlayInBlockDig.a(SourceFile:40) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.PacketPlayInBlockDig.a(SourceFile:10) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [spigot.jar:git-Spigot-db6de12-07c3001]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) [?:1.7.0_91]
    at java.util.concurrent.FutureTask.run(FutureTask.java:262) [?:1.7.0_91]
    at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot.jar:git-Spigot-db6de12-07c3001]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot.jar:git-Spigot-db6de12-07c3001]
    at java.lang.Thread.run(Thread.java:745) [?:1.7.0_91]
Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: -1
    at java.lang.String.substring(String.java:1911) ~[?:1.7.0_91]
    at com.worldcretornica.plotme_core.PlotMeCoreManager.getIdX(PlotMeCoreManager.java:43) ~[?:?]
    at com.worldcretornica.plotme_core.SqlManager.getPlot(SqlManager.java:859) ~[?:?]
    at com.worldcretornica.plotme_core.PlotMapInfo.getPlot(PlotMapInfo.java:33) ~[?:?]
    at org.wargamer2010.signshop.hooks.PlotMeHook.canBuild(PlotMeHook.java:38) ~[?:?]
    at org.wargamer2010.signshop.hooks.HookManager.canBuild(HookManager.java:51) ~[?:?]
    at org.wargamer2010.signshop.listeners.sslisteners.SimpleBlockProtector.onSSLinkEvent(SimpleBlockProtector.java:17) ~[?:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_91]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[?:1.7.0_91]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_91]
    at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_91]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot.jar:git-Spigot-db6de12-07c3001]
    ... 30 more