The only thing I can think of is that you don’t have “essentialmode” in your “AutoStartResources” list in your .yml file…
If not, try to re-install the plugin following the instuctions provided in the main thread.
Installation: Extract the folder to your resources, append “essentialmode” to your AutoStartResources. Change the MySQL data in server/player/login.lua, and last do not forget to import the provided sql file.
I could be wrong but, with the information you’ve given that’s my best guess. If you still need help, I suggest you ask the creator of essentialmode @Kanersps in PMs or on his thread.