Bukkit

What steps will reproduce the problem?
1. /ad c test 12 some tekst
2. /ad del test
3. NPE in console and didn't remove

org.bukkit.command.CommandException: Unhandled exception executing command 'ad' in plugin ShopAds2 v0.84
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:166)
        at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:479)
        at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:821)
        at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:781)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:764)
        at org.getspout.spout.SpoutNetServerHandler.a(SpoutNetServerHandler.java:106)
        at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:34)
        at net.minecraft.server.NetworkManager.b(NetworkManager.java:229)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:113)
        at org.getspout.spout.SpoutNetServerHandler.a(SpoutNetServerHandler.java:172)
        at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:567)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:459)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: java.lang.NullPointerException
        at org.bukkit.plugin.PluginBase.getName(PluginBase.java:29)
        at org.bukkit.plugin.PluginBase.equals(PluginBase.java:25)
        at java.util.ArrayList.remove(ArrayList.java:448)
        at org.hpiz.ShopAds2.Shop.ShopHandler.removeShop(ShopHandler.java:121)
        at org.hpiz.ShopAds2.Command.ShopAdsCommand.delete(ShopAdsCommand.java:219)
        at org.hpiz.ShopAds2.Command.ShopAdsCommand.playerCommand(ShopAdsCommand.java:73)
        at org.hpiz.ShopAds2.Command.ShopAdsCommand.onCommand(ShopAdsCommand.java:30)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)
        ... 14 more

11:25:41 [SEVERE] java.lang.NullPointerException 11:25:41 [SEVERE] at org.bukkit.plugin.PluginBase.getName(PluginBase.java:29) 11:25:41 [SEVERE] at org.bukkit.plugin.PluginBase.equals(PluginBase.java:25) 11:25:41 [SEVERE] at java.util.ArrayList.remove(ArrayList.java:448) 11:25:41 [SEVERE] at org.hpiz.ShopAds2.Shop.ShopHandler.removeShop(ShopHandler.java:121) 11:25:41 [SEVERE] at org.hpiz.ShopAds2.Util.Messaging.AdvertisementMessage.advertise(AdvertisementMessage.java:19) 11:25:41 [SEVERE] at org.hpiz.ShopAds2.Threads.AnnounceThread.run(AnnounceThread.java:80) 11:25:41 [SEVERE] at org.bukkit.craftbukkit.scheduler.CraftWorker.run(CraftWorker.java:34) 11:25:41 [SEVERE] at java.lang.Thread.run(Thread.java:636)