GriefPrevention doesn't work

Hey everyone, so recently i decided to start a survival server, and i'm still setting it up, i installed griefprevention, but when me or someone else places a chest to create their claim, nothing happens. I can use the griefprevention help plugin, access all the commands, but claiming doesn't work, neither the stick or the golden shovel, i've checked config and yes, it's enabled on my actual world. Here's a list of my plugins:

-ClearLag
-Essentials
-Healthbar
-PermissionsEX
-PunishMental
-SimpleRename
-WorldBorder
-WorldEdit
-WorldGuard

I checked console and found an error regarding griefprevention, that happens when i place a chest or use any of the tools

'[Server] ERROR Could not pass event PlayerInteractEvent to GriefPrevention v16.6'


[[UPDATE]]

I uninstalled every plugin i had, and downloaded multiple griefprevention verions, i tested 1 by 1, and i always got the same error:

ERROR Could not pass event BlockPlaceEvent to GriefPrevention v16.6, i also started getting some other errors, but idk if they have to do with griefprevention

http://pastebin.com/3hDRa73Y

 

Seems you are running an outdated version. Make sure your server is on 1.11 and you have the newest GriefPrevention version.