ExternalProject_Add doesn't install the Release configuration of the project - cmake

Question

EDIT: I have found a probable cause but I do not understand why: the last line in the below script Project(Externals) when removed fixes my issue. So the question now why??
cmake_minimum_required(VERSION 2.8)
include(ExternalProject)
MACRO(EXTERNAL_DEF aNewTargetName aPathToSource)
ExternalProject_Add(
${aNewTargetName}
PREFIX ${CMAKE_INSTALL_PREFIX}
SOURCE_DIR ${aPathToSource}
TMP_DIR "${CMAKE_INSTALL_PREFIX}/tmp/${CMAKE_BUILD_TYPE}"
DOWNLOAD_DIR "${CMAKE_INSTALL_PREFIX}/src/${CMAKE_BUILD_TYPE}"
BINARY_DIR "${CMAKE_INSTALL_PREFIX}/src/${CMAKE_BUILD_TYPE}/${aNewTargetName}-build"
STAMP_DIR "${CMAKE_INSTALL_PREFIX}/src/${CMAKE_BUILD_TYPE}/${aNewTargetName}-stamp"
CMAKE_ARGS
-DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
-DCMAKE_BUILD_TYPE:STRING=${CMAKE_BUILD_TYPE}
--debug-output
BUILD_COMMAND "${CMAKE_COMMAND}" --build
"${CMAKE_INSTALL_PREFIX}/src/${CMAKE_BUILD_TYPE}/${aNewTargetName}-build" --config "${CMAKE_BUILD_TYPE}"
#INSTALL_DIR "${CMAKE_INSTALL_PREFIX}"
)
ENDMACRO()
get_filename_component(zlibAbsPath "./zlib" ABSOLUTE)
EXTERNAL_DEF(zlib_external ${zlibAbsPath})
Project(Externals)
I invoke cmake on the above CMakeLists.txt file with CMAKE_INSTALL_PREFIX set to let's say "d:\externals" and CMAKE_BUILD_TYPE set to "Release"
Expectation:
I would expect only the Release configuration to get built. And after it gets built I would expect it to get installed in D:\externals\bin\zlib.dll.
Problem:
In reality, ExternalProject_Add builds both a Debug and a Release, and installs the debug version of the dll in D:\externals\bin\zlibd.dll
Isn't my build script correct? What am I doing wrong?
EDIT:
some more info. I just noticed. In the generated D:\externals\src\Release\zlib_external-build\zlib.sln, the INSTALL target is not selected to build at all. If I check it to build for the Release configuration then hit "Build" from visual studio, the INSTALL target builds and installs the files where I expect them. I have no idea what's going on...

Answer 1

CMAKE_BUILD_TYPE only work with single-configuration projects
you can change to:
BUILD_COMMAND ""
INSTALL_COMMAND
${CMAKE_COMMAND}
--build .
--target install
--config Release
BUILD_ALWAYS 1

Answer 2

Use DCMAKE_CFG_INTDIR variable.
...
CMAKE_ARGS
...
-DCMAKE_CFG_INTDIR=Release