People have to be OP on my server to talk HELP!

I have tried adding modify.world as I saw on Bukkit forums but it is still not working, please help


groups:

groups:
Default:
default: true
permissions:
- -bukkit.command.kill
inheritance:
- g:groupmanager_default
- g:bukkit_default
- g:essentials_default
- g:towny_default
- essentials.afk
- essentials.help
- essentials.helpop
- essentials.ignore
- essentials.mail
- essentials.mail.send
- essentials.me
- essentials.motd
- essentials.msg
- essentials.rules
- essentials.whois
- essentials.suicide
- essentials.warp
- essentials.signs.use.warp
- essentials.tpa
- essentials.tpaccept
- essentials.tpahere
- essentials.tpdeny
- essentials.balance
- essentials.spawn
- essentials.delhome
- essentials.home
- essentials.sethome
- essentials.signs.use.buy
- essentials.signs.use.sell
- essentials.signs.use.balance
- essentials.signs.use.free
- chest.shop*
- skybukkit.create*
- skybukkit.party*
- skybukkit.destroy*
info:
prefix: '&e'
build: false
suffix: '&e[&5D&e]'
Builder:
default: false
permissions: []
inheritance:
- default
- g:essentials_builder
- g:towny_builder
info:
prefix: '&2'
build: true
suffix: ''
Moderator:
default: false
permissions: []
inheritance:
- builder
- g:groupmanager_moderator
- g:bukkit_moderator
- g:essentials_moderator
- g:towny_moderator
- g:vanish_moderator
info:
prefix: '&5'
build: true
suffix: ''
Admin:
default: false
permissions: []
inheritance:
- moderator
- g:groupmanager_admin
- g:bukkit_admin
- g:essentials_admin
- g:towny_admin
- g:vanish_admin
info:
prefix: '&c'
build: true
suffix: '&e[&9A&e]'
Owner:
default: false
permissions:
- '*'
- -vanish.*
inheritance:
- admin
info:
prefix: '&4'
build: true
suffix: '&e[&5O&e]'