CMake cannot find source file

edit

Hi guys,

I'm using ROS kinetic on a Navio2 board, and I've been working on a project in a catkin workspace. I edited the CMakeLists.txt file to add an executable, but every time I attempt to run catkin_make, I get the following error:

CMake Error at link/CMakeLists.txt:201 (add_executable):
   Cannot find sourcefile:

    link/src/roscomm.cpp

  Tried extensions .c .C .c++ .cc .cpp .cxx .m .M .mm .h .hh .h++ .hm .hpp .hxx .in .txx

CMake Error: CMake can not determine linker language for target: roscomm
CMake Error: Cannot determine link language for target "roscomm".
-- Generating done
-- Build files have been written to: /home/pi/ros_ws/build
Invoking "cmake" failed

I know for sure that this file exists, and I've tried using just roscomm.cpp instead of link/src/roscomm.cpp.

Edit:

The full path is ~/ros_ws/src/link/src/roscomm.cpp

The CMakeLists.txt is as follows:

cmake_minimum_required(VERSION )
project(link) 

find_package(catkin REQUIRED COMPONENTS  
  roscpp
  rospy
  sensor_msgs
  std_msgs  
)

catkin_package() 

include_directories(
  ${catkin_INCLUDE_DIRS}
)

add_executable(roscomm link/src/roscomm.cpp)
target_link_libraries(roscomm ${catkin_INCLUDE_DIRS})

Any help would be great, thanks