Windows Phone 8 preprocessor directive doesn't apply to mixed solution

Question

I have a couple of similar WP8 solutions with common C++ projects for back-end. I also

I need to apply preprocessor directive to one of the solutions (it should be read by C++ back-end for this particular package) for backend to change behavior according to this solution.

Applying preprocessor directive to affect backend behavior worked for Win8/Win8.1 solutions, but it doesn't work for WP8 C# start-up projects.

What is the course of action in this case?

Answer 1

I made a copy of C++ backend project with the same content and added preprocessor directive to this project. A simple workaround and it worked.