iAuction Potion Error

... 15 more [
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40) [
at couk.rob4001.iauction.AuctionCommand.onCommand(AuctionCommand.java:63) [
at couk.rob4001.iauction.AuctionCommand.auctionStart(AuctionCommand.java:208) [
at couk.rob4001.iauction.Auction.start(Auction.java:48) [
Caused by: java.lang.NullPointerException [
at net.minecraft.server.ThreadServerApplication.run(SourceFile:539) [
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:408) [
at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:476) [
at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:212) [
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:583) [
at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30) [
at net.minecraft.server.ServerConnection.b(SourceFile:35) [
at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:109) [
at net.minecraft.server.NetworkManager.b(NetworkManager.java:281) [
at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:44) [
at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:807) [
at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:825) [
at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:878) [
at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:492) [
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:168) [
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42) [
org.bukkit.command.CommandException: Unhandled exception executing command 'auction' in plugin iAuction v4.3.1 [
2012-08-07 19:57:11 [SEVERE] null