Bukkit

Server: CraftBukkit version git-Spigot-b66ad9e-e1fb9cb (MC: 1.12.2) (Implementing API version 1.12.2-R0.1-SNAPSHOT)

Citizens: v2.0.22-SNAPSHOT (build 1497)

Sentinel: v1.4.5 (build 155)

Denizen: v1.0.2-SNAPSHOT (buid 1644)

dtlTraders: 3.5.4

I thought I would give this a try to replace ShopKeepers on my server. However it does not seem to work. 

I notice in the docs and video that when you use a stick and right click on the npc the inventory box opens and has the 3 blocks on the bottom right for mode selection. When I open mine I have all empty slots. No configuration or mode selection blocks. 

I did disable ShopKeepers thinking it might be a conflict but that did not fix it.

Is this compatible with MC 1.12.2?

Are you sure you are in manager mode? 

Did it say "Enabling manager mode"? 

In the recreation version of dtlTraders you can type your prices in the GUI instead of using blocks ;) use 5.0.0 or higher