Error esx_society


I have a problem with esx_society.
This returns me the following error:

[ script:esx_society] SCRIPT ERROR: @esx_society/server/main.lua:235: attempt to index a nil value (field ‘?’)
[ script:esx_society] > ref (@esx_society/server/main.lua:235)
[ script:esx_society] > (@mysql-async/mysql-async.js:15543)

This error causes when we go to see the list of employees in the menu of company bosses.
We have already tried a change of the script as well as reloading the database so to redo all the grade-jobs.

We hope and need valuable help. Thanks to anyone who might try to help us.