[Help!!!]

I've been trying to get tekkit to work on my bukkit server for some time now. I downloaded the launcher and everything works fine in single player. But when i try to put an tekkit item in my hot bar from the item menu, i get kicked from my server and i get this message on the pail server manager.

16:55:38 [sEVERE] java.lang.NullPointerException

2012-03-25 16:55:38 [sEVERE] at net.minecraft.server.ItemStack.setData(ItemStack.java:153)

2012-03-25 16:55:38 [sEVERE] at net.minecraft.server.ItemStack.<init>(ItemStack.java:39)

2012-03-25 16:55:38 [sEVERE] at net.minecraft.server.Packet.b(Packet.java:150)

2012-03-25 16:55:38 [sEVERE] at net.minecraft.server.Packet107SetCreativeSlot.a(SourceFile:25)

2012-03-25 16:55:38 [sEVERE] at net.minecraft.server.Packet.a(Packet.java:79)

2012-03-25 16:55:38 [sEVERE] at net.minecraft.server.NetworkManager.h(NetworkManager.java:149)

2012-03-25 16:55:38 [sEVERE] at net.minecraft.server.NetworkManager.c(NetworkManager.java:265)

2012-03-25 16:55:38 [sEVERE] at net.minecraft.server.NetworkReaderThread.run(SourceFile:76)

2012-03-25 16:55:38 [iNFO] ebs100 lost connection: disconnect.genericReason

What do i need to do to get the server running so i can use tekkit with my friends?