Error with NEI when in multiplayer

[danlapid]

Hey I got a custom built server and client modpack for me and a few friends and I wanted to update to 3.1.6 but it seems I am having a few problems when I am logging in from the client and log into the server from an op'd user but when I try to take something from NEI I get the following error

java.lang.NoClassDefFoundError: railcraft/common/utility/RollingMachineCraftingManager

at codechicken.nei.plugins.railcraft.RollingMachineRecipeHandler.loadCraftingRecipes(RollingMachineRecipeHandler.java:57)

at codechicken.nei.TemplateRecipeHandler.getRecipeHandler(TemplateRecipeHandler.java:196)

at codechicken.nei.GuiCraftingRecipe.hasRecipe(GuiCraftingRecipe.java:31)

at codechicken.nei.NEIController.onItemEvent(NEIController.java:298)

at codechicken.nei.ItemPanelStack.handleClick(ItemPanelStack.java:24)

at codechicken.nei.ItemPanel.handleClick(ItemPanel.java:95)

at codechicken.nei.LayoutManager.onClick(LayoutManager.java:29)

at codechicken.nei.NEIController.replacementClickHandler(NEIController.java:32)

at gb.a(GuiContainer.java:266)

at vp.f(SourceFile:122)

at gb.f(GuiContainer.java:425)

at sr.f(SourceFile:248)

at vp.i(SourceFile:110)

at gb.i(GuiContainer.java:419)

at net.minecraft.client.Minecraft.k(Minecraft.java:1567)

at net.minecraft.client.Minecraft.x(Minecraft.java:822)

at net.minecraft.client.Minecraft.run(Minecraft.java:750)

at java.lang.Thread.run(Unknown Source)

Caused by: java.lang.ClassNotFoundException: railcraft.common.utility.RollingMachineCraftingManager

at java.net.URLClassLoader$1.run(Unknown Source)

at java.net.URLClassLoader$1.run(Unknown Source)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

... 18 more

--- END ERROR REPORT 62ef966 ----------

(just to be clear, it doesn't happen when playing SSP)

[danlapid]

any chance its a problem with the NEI plugin? it might be outdated