Error

[MinecraftRemoteAdmin] Task #5090 for MinecraftRemoteAdmin v0.1.1 BETA generated an exception
java.lang.NoClassDefFoundError: org/bukkit/craftbukkit/v1_5_R3/entity/CraftPlayer
	at com.stabbedbit.minecraftRemoteAdmin.bukkit.variables.PingRunner.run(PingRunner.java:24)
	at org.bukkit.craftbukkit.v1_6_R1.scheduler.CraftTask.run(CraftTask.java:53)
	at org.bukkit.craftbukkit.v1_6_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:345)
	at net.minecraft.server.v1_6_R1.MinecraftServer.t(MinecraftServer.java:523)
	at net.minecraft.server.v1_6_R1.DedicatedServer.t(DedicatedServer.java:226)
	at net.minecraft.server.v1_6_R1.MinecraftServer.s(MinecraftServer.java:487)
	at net.minecraft.server.v1_6_R1.MinecraftServer.run(MinecraftServer.java:420)
	at net.minecraft.server.v1_6_R1.ThreadServerApplication.run(SourceFile:582)