FTB Server Writing Desk Issue

14:48:19  [SEVERE] java.lang.Exception
14:48:19  [SEVERE] 	at zz.a(Chunk.java:1095)
14:48:19  [SEVERE] 	at yc.a(World.java:3305)
14:48:19  [SEVERE] 	at com.xcompwiz.mystcraft.block.BlockWritingDesk.g(BlockWritingDesk.java:230)
14:48:19  [SEVERE] 	at zz.a(Chunk.java:787)
14:48:19  [SEVERE] 	at yc.a(World.java:768)
14:48:19  [SEVERE] 	at yc.c(World.java:746)
14:48:19  [SEVERE] 	at yc.d(World.java:987)
14:48:19  [SEVERE] 	at com.xcompwiz.mystcraft.item.ItemWritingDesk.a(ItemWritingDesk.java:73)
14:48:19  [SEVERE] 	at ur.a(ItemStack.java:135)
14:48:19  [SEVERE] 	at ir.a(ItemInWorldManager.java:580)
14:48:19  [SEVERE] 	at iv.a(NetServerHandler.java:906)
14:48:19  [SEVERE] 	at fk.a(Packet15Place.java:79)
14:48:19  [SEVERE] 	at cg.b(TcpConnection.java:467)
14:48:19  [SEVERE] 	at iv.d(NetServerHandler.java:220)
14:48:19  [SEVERE] 	at iw.b(NetworkListenThread.java:57)
14:48:19  [SEVERE] 	at ht.b(DedicatedServerListenThread.java:34)
14:48:19  [SEVERE] 	at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:870)
14:48:19  [SEVERE] 	at ho.r(DedicatedServer.java:309)
14:48:19  [SEVERE] 	at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:746)
14:48:19  [SEVERE] 	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:633)
14:48:19  [SEVERE] 	at fy.run(ThreadMinecraftServer.java:16)