Problem/Bug essentials

idk what im doing wrong i have an issue with sign shop if im op i can use evrything
but normal player who joins server cant buy enthing plz help my this is what i have in the permessionEx

Code:

groups:
  Gracz:
    options:
      default: true
    permissions:
    - -bukkit.commands.*
    - -minecraft.commands.*
    - essentials.spawn
    - essentials.home
    - essentials.sethome
    - essentials.tpa
    - essentials.tpaccept
    - essentials.tpdeny
    - essentials.msg
    - automessage.receive.default
    - essentials.helpop
    - essentials.chat.url
    - essentials.warp.*
    - essentials.kit
    - essentials.kits.Gracz
    - essentials.kits.jedzenie
    - essentials.warp
    - Signshop.Signs.Sell
    - Signshop.Signs.Buy

( gracz means in polisch player if someone asks )