Why can't I add code to my project?

[SwampGerman (alexis Lallemand Desmarais)]

Every time i try to add code to my project in UE4 i get this error message : Failed to add class X. Failed to generate project files. I have look at my Windows environmental variable VSCOMNTOOLS and it seems to be pointing in the right place.
I try to add code this way:

1. Create New Project with blank template.
2. File → Add code to project → Chose any parent class and they all fail.

The file gets created but i receive the error message and then it tells me that I already have a class with this name.

I have VS 2012 Ultimate.

[Stephen_Ellis]

Hi SwampGerman,

Visual Studio 2013 is required for development. Please view these documentation pages for additional information:

• https://docs.unrealengine.com/latest/INT/Programming/QuickStart/1/index.html
• https://docs.unrealengine.com/latest/INT/Programming/Development/VisualStudioSetup/index.html
• https://docs.unrealengine.com/latest/INT/GettingStarted/RecommendedSpecifications/index.html

Cheers