What am I doing wrong when building krusader for plasma 5 via Cmake?

Question

CMake

I'm trying to build krusader according to the instructions from
https://github.com/KDE/krusader/blob/master/INSTALL
Qt installed
Where should I look to understand what he wants from me?

[email protected]:~/krusader/build$ cmake -DCMAKE_INSTALL_PRFIX=/opt/krusader -DCMAKE_CXX_FLAGS="-O2 -fPIC" ..
-- The C compiler identification is GNU 5.3.1
-- The CXX compiler identification is GNU 5.3.1
-- 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
-- Detecting C compile features
-- Detecting C compile features - 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
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Warning at /usr/local/share/ECM/modules/ECMQueryQmake.cmake:22 (message):
  Failed call: qmake-qt5 -query "QT_INSTALL_PREFIX"
Call Stack (most recent call first):
  /usr/local/share/ECM/kde-modules/KDEInstallDirs.cmake:431 (query_qmake)
  CMakeLists.txt:25 (include)


CMake Error at /usr/local/share/ECM/modules/ECMQueryQmake.cmake:23 (message):
  QMake call failed: No such file or directory
Call Stack (most recent call first):
  /usr/local/share/ECM/kde-modules/KDEInstallDirs.cmake:431 (query_qmake)
  CMakeLists.txt:25 (include)


-- Configuring incomplete, errors occurred!
See also "/home/sea/krusader/build/CMakeFiles/CMakeOutput.log".