Bukkit

What steps will reproduce the problem?
1. stoped working from one day to the other!

What is the expected output? What do you see instead?
no output only error in server log!

What version of the product are you using?
newest 1.7.2

Do you have an error log of what happened?
Exception in thread "Thread-90"  <- OR 91,92,93 blablabla
[13:04:08] [Thread-90/WARN]: java.lang.NullPointerException
[13:04:08] [Thread-90/WARN]:     at com.afforess.minecartmania.chests.ItemDepositContainer.doCollection(ItemDepositContainer.java:30)
[13:04:08] [Thread-90/WARN]:     at com.afforess.minecartmania.signs.actions.DepositItemsAction.execute(DepositItemsAction.java:22)
[13:04:08] [Thread-90/WARN]:     at com.afforess.minecartmania.signs.SignAction.executeDebug(SignAction.java:36)
[13:04:08] [Thread-90/WARN]:     at com.afforess.minecartmania.signs.SignAction.executeAsSign(SignAction.java:32)
[13:04:08] [Thread-90/WARN]:     at com.afforess.minecartmania.signs.MMSign$1.run(MMSign.java:115)
[13:04:08] [Thread-90/WARN]:     at java.lang.Thread.run(Unknown Source)

Please provide any additional information below.
have a working wheat farm and will deposit the wheat from one chest in another but java say nope!