Hi Anderas,
thanks for help. When I installed some years ago it worked out of the box.
Ok. It is installed from SUSE Package Hub:
I have installed LADSPA plugins - they come quite automatically if you know they are missing.

Variable: There are several pathes. I chosed this one:
# export LADSPA_PATH=/usr/lib64/ladspa
Correct?

hans-christoph@LINUXSLES:~> kdenlive
Icon theme "breeze" not found.
Icon theme "breeze" not found.
KCrash: Application 'kdenlive' crashing...
KCrash: Attempting to start /usr/lib64/libexec/drkonqi from kdeinit
sock_file=/run/user/1000/kdeinit5__0
Warning: connect() failed: : No such file or directory
KCrash: Attempting to start /usr/lib64/libexec/drkonqi directly
found lsb_release
Using /proc to determine executable path
Executable is: "/usr/bin/kdenlive"
Executable exists: true
Enabling drkonqi crash catching
QSystemTrayIcon::setVisible: No Icon set
Sending SIGSTOP to process

[1]+ Stopped kdenlive
---------------
sock_file=/run/user/1000/kdeinit5__0
Warning: connect() failed: : No such file or directory

When i start KDENLIVE as su:
# kdenlive
QStandardPaths: wrong ownership on runtime directory /run/user/1000, 1000 instead of 0
"Session bus not found\nTo circumvent this problem try the following command (with Linux and bash)\nexport $(dbus-launch)"

here seems a file missing or setting wrong.