[CMake] Trying to setup make folder configuration on linux

[Louis Hoefler]

Hello everyone,
i currently try to setup a make configuration where the debug and the 
release version of my programm should be built into different subfolders.
My problem is that the installation does not find the created executable.
The directory stucture looks like this:
/massmailer
   CmakeLists.txt
   build_script.sh
      cd Release
      cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr ../
      make
      make install
/massmailer/Debug
/massmailer/Release
/massmailer/massmailer
   main.cpp
   CmakeLists.txt

The installation stops with:

-- Configuring done
-- Generating done
-- Build files have been written to: /root/massmailer/Debug
[100%] Built target massmailer
-- Configuring done
-- Generating done
-- Build files have been written to: /root/massmailer/Release
[100%] Built target massmailer
Install the massmailer release now [Yes/n]? Yes
[100%] Built target massmailer
Install the project...
-- Install configuration: "Release"
CMake Error at massmailer/cmake_install.cmake:36 (FILE):
   file INSTALL cannot find "/root/massmailer/massmailer/massmailer".
Call Stack (most recent call first):
   cmake_install.cmake:37 (INCLUDE)


make: *** [install] Error 1

How do I solve this error?

Thank you, Louis