FTB Ulti Reloaded

[OfficialXanoX]

Hello i have a problem with a server im hosting.
I made a Iron tank 7x7x8.
but i have to replace 2 blocks to make it multiblock everytime i log in go to nether and so on.
allso i get this error in server.
and all items bug out. pickaxe on the head duble of all and so on.
but when i open a chest or uther multiblock it goes back to normal. PLZ HELP!


[06:56:05] [Server thread/FATAL] [net.minecraft.server.MinecraftServer]: Error executing task
java.util.concurrent.ExecutionException: java.lang.IndexOutOfBoundsException: Index: 41, Size: 38
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_171]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_171]
at net.minecraft.util.Util.func_181617_a(SourceFile:47) [h.class:?]
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:723) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:397) [nz.class:?]
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_171]
Caused by: java.lang.IndexOutOfBoundsException: Index: 41, Size: 38
at java.util.ArrayList.rangeCheck(Unknown Source) ~[?:1.8.0_171]
at java.util.ArrayList.get(Unknown Source) ~[?:1.8.0_171]
at mods.railcraft.common.gui.containers.RailcraftContainer.func_184996_a(RailcraftContainer.java:118) ~[RailcraftContainer.class:?]
at net.minecraft.network.NetHandlerPlayServer.func_147351_a(NetHandlerPlayServer.java:1162) ~[pa.class:?]
at net.minecraft.network.play.client.CPacketClickWindow.func_148833_a(CPacketClickWindow.java:38) ~[lf.class:?]
at net.minecraft.network.play.client.CPacketClickWindow.func_148833_a(CPacketClickWindow.java:12) ~[lf.class:?]
at net.minecraft.network.PacketThreadUtil$1.run(SourceFile:13) ~[hv$1.class:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_171]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_171]
at net.minecraft.util.Util.func_181617_a(SourceFile:46) ~[h.class:?]
... 5 more
[07:00:51] [Server thread/INFO] [net.minecraft.network.NetHandlerPlayServer]: zedofswe lost connection: Disconnected