Solved Plugin Reference

So i've been downloading plugins like ServerRewards and Kits and they seem to have plugin reference to Economics, but when I put the

Code:

[PluginReference] private Economics;

it seems to have an error anyone know why?

 

Economics does not exist in the current context

 

With the addition of Plugin now, it says i'm missing an assembly but these are my current references

 

Nah my fault, i did a nooby mistake, I forgot to add Oxide.Core.Plugins, i put Oxide.Plugins