SDK User defined class

Hi

I'm building a C++ plugin and I'm trying to setup a user defined class that I can then use in my main cpp file. I'm using Visual Studio.

I'm testing this with a small project based on Skeleton sample project.

I have made a completly basic class with a header and a cpp file like this: https://learn.microsoft.com/en-us/cpp/cpp/header-files-cpp?view=msvc-170 

The header file is located in the folder called "Header Files", just like the other header files. The cpp file is in the root along side the main cpp file.

I get this intelligense error:

"Severity Code Description Project File Line Suppression State
Error (active) E1696 cannot open source file "my_class.h" TestPlugin"

If I try to build I get this error:

"Severity Code Description Project File Line Suppression State
Error C1083 Cannot open include file: 'my_class.h': No such file or directory TestPlugin"

Is there anything I need to do to create my own custom headers and classes?

Thanks,

Jakob