Bukkit

What steps will reproduce the problem?
1. turtle.turnLeft() in a text file
2. Run /cct text file
3. Error appears

What is the expected output? What do you see instead?
The dispenser to turn but it shows "Error on line #" (the number is 9, 14, 12, 6 or 10)

What version of the product are you using?
First one

Do you have an error log of what happened?
2013-02-16 10:27:29 [WARNING] [ComputerCraft] Task #71 for ComputerCraft v1.0 generated an exception
java.lang.ClassCastException: org.bukkit.material.MaterialData cannot be cast to org.bukkit.material.Dispenser
    at me.metaljulien.bukkit.CC.Turtle$1.run(Turtle.java:236)
    at org.bukkit.craftbukkit.v1_4_R1.scheduler.CraftTask.run(CraftTask.java:53)
    at org.bukkit.craftbukkit.v1_4_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:344)
    at net.minecraft.server.v1_4_R1.MinecraftServer.r(MinecraftServer.java:530)
    at net.minecraft.server.v1_4_R1.DedicatedServer.r(DedicatedServer.java:224)
    at net.minecraft.server.v1_4_R1.MinecraftServer.q(MinecraftServer.java:494)
    at net.minecraft.server.v1_4_R1.MinecraftServer.run(MinecraftServer.java:427)
    at net.minecraft.server.v1_4_R1.ThreadServerApplication.run(SourceFile:849)

Please provide any additional information below.
Other than that, works brilliantly!