CMake 'no rule to make target' with external library - c++

Question

I am trying link one of my programs to libevent. I am using CMake as build system. My project structure is as follows:
my_project
├── CMakeLists.txt
├── README.md
├── build
│  └── Build stuff
└── software
├── README.md
├── CMakeLists.txt
├── include
├── libraries
│   ├── libevent
│ │   └── CMakeLists.txt
│   └── anotherlibrary
│      └── CMakeLists.txt
├── prog1
│   ├── CMakeLists.txt
├── prog2
│   ├── CMakeLists.txt
└── prog3
└── CMakeLists.txt
CMakeList.txt of prog1 (the one that's needs to be linked to libevent)
cmake_minimum_required(VERSION 2.6)
project (prog1)
file(GLOB prog1
"*.h"
"*.cpp"
)
include_directories("${PROJECT_INCLUDE_DIR}/libevent/include")
add_executable(${PROJECT_NAME} ${prog1})
target_link_libraries(${PROJECT_NAME} event_core)
But when I build the project make can't find the library build by libevent. it searched for: libraries/libevent/lib/libevent_core.a this is the wrong path since libevent builds it libs inside: my_project/build/software/libraries/libevent/lib/libevent_core.a
How do I tell CMake to search there for the library? I already added the following lines to my Cmake file but this wasn't working
link_directories(/my_project/build/software/libraries/libevent/lib/)
SET(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/build/lib)
SET(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_SOURCE_DIR}/build/bin)
Anyone a suggestion?

Answer 1

I fixed the problem myself by removing the content from the build directory and re running cmake .. inside the build directory.
I think CMake was somehow not aware of the changes I made and by rebuilding the project the problem was fixed.