thanks man
this is how it needs to look from HA mqtt interface, and beware, at least on my nexus, it take some time to do what was ordered, kind of like the Rudolf Diesel minute’s silence before such a banger comes to life 
edit:
wallpanel/mywallpanel/ needs to be replaced with what you did set in Base Tpoic set under the mqtt settings in the wall panel if you did change them from stock settings.
attention, if you safe the last dash behind mywallpanel, you need to give the command as
wallpanel/mywallpanelcommand this does work too.