error

[17:25:54] [pool-3-thread-7/WARN]: org.apache.commons.lang.UnhandledException: Plugin Anti-Bot v1.0 generated an exception while executing task 9
	at org.bukkit.craftbukkit.v1_7_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:56)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NoSuchMethodError: org.bukkit.Server.getOnlinePlayers()Ljava/util/Collection;
	at org.mcstats.Metrics.postPlugin(Metrics.java:335)
	at org.mcstats.Metrics.access$400(Metrics.java:57)
	at org.mcstats.Metrics$1.run(Metrics.java:223)
	at org.bukkit.craftbukkit.v1_7_R1.scheduler.CraftTask.run(CraftTask.java:53)
	at org.bukkit.craftbukkit.v1_7_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
	... 3 more