[beagleboard] "no display name and no $display environment variable"

Thanks for your comments. The f/ph type was quickly solved… (thanks!). But then it still does not work. After a couple of days experimenting and googling I get lost. I know most systemd commend by heart now… ;-). Now I get the error: ac.service is not loaded properly. Error: invalid argument. My service is now:

Description …
After = graphical.target
Type = idle
XAUTHORITY {no arguments needed?}
ExecStart = /home/debian/eme {etc to run Python script and make log file}

I do hope you can get me going.
Thanks in advance,
PS: I considered using autostart that works perfect on my two year old Debian on another system with LXDE. Now LXQT is used and I can not find this anymore.