I added a new project in my VS solution already containing 3 projects. However, I couldn't import this project into the the files of existing project with the help of "using" keyword.
PS: The newly added project is a MVC web application and the older projects are C# projects to develop windows form application. My ultimate goal is to pass data from my MVC web application to the classes of existing projects.
I figured it out. I had to reference the projects. Right Click -> add reference. Hope this helps to some having same issue.