CrackShot Placing Levers Permmisions

Hello! I would ike to appoligize for the title as it could be confusing, i really didn't know how to name it, but on to the point.

If you have used a plugin called crack shot, u know there's a weapon called C4. Which as it sounds, is a remote explosive.

I also have GroupManager for permmisions, KingKits for kits, WorldGuard for protection, and essentials.

I have my pvp area as a region, and players have told me the c4 dosen't work as they don't have permission to place the lever/head (c4). I have given them the crackshot.bypass.C4 permission.

I also has given the region build to allow, but they still can't place the c4. Help!