Hi,

Two questions

Is the file actually included in the project/solution tree? Does it have a little red exclamation mark against it?

Does #include "src/asf.h" work?

Quick update, I was able to recreate this problem and as it turns out it has everything to do with the fact that when I right click the project and choose Add Arduino Library and add my libraries to my project it copies the source code from these libraries into my project under src and include.  This is the error I get when I included the Chronos library.  

Calendar.cpp: 26:42: fatal error: chronosinc/schedule/Calendar.h: No such file or directory
   #include "chronosinc/schedule/Calendar.h"
   compilation terminated

     An error was encountered during the 'Deep Search' library discovery process.
Debug build failed for project 'MyTestProject'

I can eliminate this error by forcing the compiler to include the path to chronosinc/schedule/Calendar.h via the Extra c flags and Extra cpp flags, but I still end up with a link error.  But if I simply delete the directory hierarchies "include" and "src" from my project it compiles and links just fine without adding the Extra c flags and Extra cpp flags.  

So my question now is, am I adding the Arduino libraries to my project incorrectly?  I tried to add them as I usually do via Atmel Studio, right click on the Project -> Libraries and choose Add.  When I add them that way I also manually add the Include directories to Toolchain -> C Compiler and Toolchain -> C++ compiler but that doesn't work with Visual Micro as it overwrites any edits I perform to this setting.  

What is the correct way to add an Arduino library to a Visual Micro Arduino project?