a tileentity type has throw an exception

[Cixxar]

Hey, I keep getting this error on my server from SC - and the error message says to tell you about it.
I makes the whole server lag and sometimes crash.

[20:56:29] [Server thread/ERROR] [FML/]: A TileEntity type vswe.stevescarts.TileEntities.TileEntityDistributor has throw an exception trying to write state. It will not persist. Report this to the mod author
java.lang.RuntimeException: class vswe.stevescarts.TileEntities.TileEntityDistributor is missing a mapping! This is a bug!
at net.minecraft.tileentity.TileEntity.func_145841_b(TileEntity.java:80) ~[aor.class:?]
at vswe.stevescarts.TileEntities.TileEntityDistributor.func_145841_b(TileEntityDistributor.java:78) ~[TileEntityDistributor.class:?]
at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75820_a(AnvilChunkLoader.java:370) [aqk.class:?]
at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75816_a(AnvilChunkLoader.java:197) [aqk.class:?]
at net.minecraft.world.gen.ChunkProviderServer.func_73242_b(ChunkProviderServer.java:256) [ms.class:?]
at net.minecraft.world.gen.ChunkProviderServer.func_73151_a(ChunkProviderServer.java:302) [ms.class:?]
at net.minecraft.world.WorldServer.func_73044_a(WorldServer.java:809) [mt.class:?]
at net.minecraft.server.MinecraftServer.func_71267_a(MinecraftServer.java:318) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:569) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685) [li.class:?]