Server keeps losing connection

[rabidbear99]

My server loses conection after start up. Here is the message:

23:28:52 [sEVERE] Unexpected exception

java.lang.NoSuchMethodError: buildcraft.api.PowerProvider.useEnergy(IIZ)I

at buildcraft.factory.TilePump.q_(TilePump.java:84)

at net.minecraft.server.World.tickEntities(World.java:1189)

at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:559)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:457)

at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)

PLEASE HELP FAST!!!!