Dwafforge error code

2012-05-29 16:45:56 [WARNING] Task of 'DwarfForge' generated an exception
java.lang.ClassCastException: org.bukkit.craftbukkit.block.CraftBlockState cannot be cast to org.bukkit.block.Furnace
    at org.simiancage.bukkit.DwarfForge.Forge.toggle(Forge.java:424)
    at org.simiancage.bukkit.DwarfForge.DFBlockListener$1.run(DFBlockListener.java:130)
    at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:126)
    at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:533)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:459)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
2012-05-29 16:45:56 [INFO] [DwarfForge] BockType= [AIR]
2012-05-29 16:45:56 [WARNING] Task of 'DwarfForge' generated an exception
java.lang.ClassCastException: org.bukkit.craftbukkit.block.CraftBlockState cannot be cast to org.bukkit.block.Furnace
    at org.simiancage.bukkit.DwarfForge.Forge.douse(Forge.java:153)
    at org.simiancage.bukkit.DwarfForge.Forge.update(Forge.java:350)
    at org.simiancage.bukkit.DwarfForge.Forge.run(Forge.java:372)
    at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:126)
    at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:533)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:459)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)