trade error

[21:18:01 INFO]: TheOnlyRealTGS issued server command: /trade accept
[21:18:01 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'trad
e' in plugin Trade v1.0
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[cus
tom.jar:git-Spigot-13716d9-0e2396c]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:14
1) ~[custom.jar:git-Spigot-13716d9-0e2396c]
        at org.bukkit.craftbukkit.v1_8_R1.CraftServer.dispatchCommand(CraftServe
r.java:645) ~[custom.jar:git-Spigot-13716d9-0e2396c]
        at net.minecraft.server.v1_8_R1.PlayerConnection.handleCommand(PlayerCon
nection.java:1115) [custom.jar:git-Spigot-13716d9-0e2396c]
        at net.minecraft.server.v1_8_R1.PlayerConnection.a(PlayerConnection.java
:950) [custom.jar:git-Spigot-13716d9-0e2396c]
        at net.minecraft.server.v1_8_R1.PacketPlayInChat.a(PacketPlayInChat.java
:26) [custom.jar:git-Spigot-13716d9-0e2396c]
        at net.minecraft.server.v1_8_R1.PacketPlayInChat.a(PacketPlayInChat.java
:53) [custom.jar:git-Spigot-13716d9-0e2396c]
        at net.minecraft.server.v1_8_R1.PacketHandleTask.run(SourceFile:13) [cus
tom.jar:git-Spigot-13716d9-0e2396c]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [
?:1.8.0_25]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_25]
        at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:6
83) [custom.jar:git-Spigot-13716d9-0e2396c]
        at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:3
16) [custom.jar:git-Spigot-13716d9-0e2396c]
        at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:6
23) [custom.jar:git-Spigot-13716d9-0e2396c]
        at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java
:526) [custom.jar:git-Spigot-13716d9-0e2396c]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_25]
Caused by: java.lang.IllegalArgumentException: Cannot measure distance between t
est and Lobby
        at org.bukkit.Location.distanceSquared(Location.java:451) ~[custom.jar:g
it-Spigot-13716d9-0e2396c]
        at de.matzefratze123.trade.CommandTrade.onCommand(CommandTrade.java:53)
~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[cus
tom.jar:git-Spigot-13716d9-0e2396c]
        ... 14 more