cmake fails to find qtcore on kde5

[fvbock]

running on latest kubuntu (15.04) i get this message when running cmake:

$ cmake CMakeLists.txt -DCMAKE_INSTALL_PREFIX=`kde4-config --prefix`
-- The C compiler identification is GNU 4.9.2
-- The CXX compiler identification is GNU 4.9.2
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
CMake Warning at /usr/share/cmake-3.0/Modules/FindQt4.cmake:616 (message):
  /usr/bin/qmake reported QT_INSTALL_LIBS as "/usr/lib/x86_64-linux-gnu" but
  QtCore could not be found there.  Qt is NOT installed correctly for the
  target build environment.
Call Stack (most recent call first):
  CMakeLists.txt:6 (find_package)


CMake Error at /usr/share/cmake-3.0/Modules/FindQt4.cmake:621 (message):
  Could NOT find QtCore.  Check
  /home/morpheus/data/dev/c++/kaption/CMakeFiles/CMakeError.log for more
  details.
Call Stack (most recent call first):
  CMakeLists.txt:6 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/morpheus/data/dev/c++/kaption/CMakeFiles/CMakeOutput.log".

installed libqtcore is:

Package: libqtcore4
Version: 4:4.8.6+git64-g5dc8b2b+dfsg-3~ubuntu6