my players say that they d'ont have permission to eat food i'm guessing thats with pex does it require a permission to eat food
I would suggest using Group Manager with Essentials rather than using PermissionsEx. I had the same issues you were having but when I switched over to Group Manager the problems had stopped. I would also suggest removing Essentials Anti Build and Essentials Protect as well, especially if you're using World Guard and World Edit. You can edit the worlds build/protections in the config file. If you wanted to turn off (example) creeper block damage you can edit that in the config file by setting the value from "true" to "false". When I had Essentials Anti Build and Essentials Protect players were reporting to me that they were unable to place lava buckets etc. Once I had removed the 2 plugins and used World Guard/World Edit as my default world permissions, everything was working fine. Hope I helped... -RC!
Or you could keep PermissionsEx since it works fine with Essentials and just add the permission essentials.build to your groups to bypass the AntiBuild and Protect problems. Removing those Essentials jars is certainly one option, but it's just as easy to configure them the way you want in the Essentials config file and let them stay.