How to get reference of business.Entity class in mvc

Hi 

I have 3 layer app.

1)Business.Entity class

2)EntityFramework.Dbconnection.

3)My_domain_mvc

i want to get ref of my entity class in dbconnection  so how can i get all class file in my dbcontext class 

I'm getting this error: but i'm alredy add ref of project in ref.....and pass ref inusing Business.entity.class;

http://my.jetscreenshot.com/29458/20161209-hnqn-39kb.png