libk.so.5 not found

[bytersproblem]

Hi, I am trying to instlal kgtk-wrapper. I built is successfully on Kubuntu 21.04. with

cmake .. -DCMAKE_INSTALL_PREFIX=/usr -DLIB_SUFFIX=64
make
sudo make install

however, when I try to launch a programm from the command line, I get

WARNING: Failed to find override library /usr/lib64/kgtk/libk.so.5
Disabled!

and thr program does not run with a KDE dialog.

Please help if possible.