1st one went through OK, then clicked again to purchase and error.

2012-11-10 18:16:11 [INFO] RootCookie issued server command: /reload
2012-11-10 18:16:14 [INFO] �[33;22mSet fly mode�[31;1m enabled �[33;22mfor �[31;1mFEVER �[35;1mRootCookie�[0;39m�[33;22m.�[m
2012-11-10 18:16:16 [INFO] [PreciousStones] RootCookie rented 1h time in Server's WOOL field for 1  [83 63 299 Fever Survival]
2012-11-10 18:16:26 [SEVERE] Could not pass event PlayerInteractEvent to PreciousStones v9.5.0-SNAPSHOT
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:341)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
    at org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:177)
    at net.minecraft.server.ItemInWorldManager.interact(ItemInWorldManager.java:366)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:650)
    at net.minecraft.server.Packet15Place.handle(SourceFile:58)
    at net.minecraft.server.NetworkManager.b(NetworkManager.java:282)
    at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:111)
    at net.minecraft.server.ServerConnection.b(SourceFile:35)
    at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30)
    at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:578)
    at net.minecraft.server.DedicatedServer.r(DedicatedServer.java:215)
    at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:495)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:428)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:818)
Caused by: java.lang.NullPointerException
    at net.sacredlabyrinth.Phaed.PreciousStones.vectors.Field.addPayment(Field.java:2453)
    at net.sacredlabyrinth.Phaed.PreciousStones.vectors.Field.rent(Field.java:2479)
    at net.sacredlabyrinth.Phaed.PreciousStones.listeners.PSPlayerListener.onPlayerInteract(PSPlayerListener.java:724)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:339)
    ... 16 more

fixed in latest build