Essentials kit error2

[12:05:55] [Server thread/INFO]: SailEGameS issued server command: /kit
[12:05:58] [Server thread/INFO]: SailEGameS issued server command: /kit Dtools
[12:05:58] [Server thread/WARN]: [Essentials] ?4Unknown item name: dpickaxe.
[12:06:04] [Server thread/INFO]: SailEGameS issued server command: /kit Color
[12:06:04] [Server thread/WARN]: [Essentials] ?4Unknown item name: writtenbook.