Support request: IC2 server issue - rubber trees

[SEVERE] Unexpected exception
java.lang.NullPointerException
at ic2.common.WorldGenRubTree.grow(WorldGenRubTree.java:60)
at ic2.common.WorldGenRubTree.a(WorldGenRubTree.java:32)
at mod_IC2.GenerateSurface(mod_IC2.java:1249)
at ModLoader.PopulateChunk(ModLoader.java:826)
at li.a(ChunkProviderServer.java:178)
at lq.a(Chunk.java:859)
at li.c(ChunkProviderServer.java:89)
at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:256)
at net.minecraft.server.MinecraftServer.s(MinecraftServer.java:175)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:315)
at cz.run(SourceFile:465)

2012-01-24 00:10:47 [INFO] Mod Loaded: mod_BuildCraftCore 2.2.12
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_BuildCraftBuilders 2.2.12
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_BuildCraftEnergy 2.2.12
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_BuildCraftFactory 2.2.12
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_BuildCraftTransport 2.2.12
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_IC2 v1.62
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_RedPowerArray 2.0pr4d
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_RedPowerCore 2.0pr4d
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_RedPowerLighting 2.0pr4d
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_RedPowerLogic 2.0pr4d
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_RedPowerMachine 2.0pr4d
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_RedPowerWiring 2.0pr4d
2012-01-24 00:10:47 [INFO] Mod Loaded: mod_RedPowerWorld 2.0pr4d