Visual Studio Web Test and Custom Extraction Rule doesn't work with custom Namespace

I am using Visual Studio Web Performance Test and custom Extraction Rules.

Problem: If the namespaces of the Extraction rules are not the project root namespace, the Performance Web Test will fail.

Request failed: Could not load file or assembly '[ProjectName], Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies.

So if I want to organize my cs files in a folder, I need to omit the folder name in the namespace, and have the anoying warning Namespace does not correspond to file location, should be '[namespaceRoot].[folder]'.

How to avoid that?

Workaround: If I copy manually the dll in the C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE, it will work, but this not an acceptable solution for me.