Bukkit

Hello, the problem is when you have chest shop and you're plugins it's don't work.
When the player put the sign the serv say to him "you don't have the permission to do that" I try with expbank.create permissions and it's don't work to.

After i go in a log for see what is the problem and the log say the player who put the sign try to hack (come chestshop).

What version of the product are you using?

craftbukkit 1.5.1

Do you have an error log of what happened?

2013-04-12 23:33:38 [SEVERE] [ChestShop] Player Ivar tried to create a fake sign. Hacking? (it's when the player create the sign [expbank])

Tanks you for you're help and sorry for my bad english, i'm french.