Project will not build after adding function or procedure to edmx

Having issues in trying to add a function/procedure to your Entity Data Model - it will not build after that ?
What's more, it works perfectly with Entity Framework version 5 ? And with 6, which you are trying now, does not ?

Well, here's the solution.

Lessons learned: there is such a thing as Entity Framework Tools for Visual Studio, and we need to make sure we have it updated/in sync with the version of Visual Studio we are using in combination with a package we have just downloaded/added to our project.

Dependencies, dependencies, dependencies...