Hi, i want to tell you a few things about your plugin to fix it.
First, the mcmmo trade doesn't work, i use the bukkit mcmmo, last version (
http://dev.bukkit.org/bukkit-plugins/mcmmo/). We use a database, but we tried without database and doesn't work.
Second, the jobs trade doesn't work, i use the jobs reborn from spigot (
https://www.spigotmc.org/resources/jobs-reborn.4216/). I think it's because it is not default jobs plugin, but i'd appreciate it if you offer support in a future release.
A suggestion: Can you create a permission to start trades? You have all the permissions except this, and it's a very useful permission.
And the last one, i found a bug to duplicate, and if you don't fix this, i can't use your plugin.
Now i'll explain the bug:
First, you trade with another, you put the item you want to duplicate on the right (one or more, if you put more, you duplicate fast), and next, you shift click with another item, and you duplicated a item.
Here's a video demostration:
https://youtu.be/KKSFbeQYJVc