Non available Element for better Thermostat

Hi folks,

i tried to control my new wall thermostat (after problems with a HMip wall thermostat) from schneider/wiser/merten with better thermostat (like all my shelly thermostat radiator valves).

Now the device within better thermostat is allways unavailable and i dont have no clue why…

These are the shown attributes from the dev tools for the value conditions.

This is the shown status info from Z2M.

I allready have added a template sensor for the current/ local temperature and assigned this to the MQTT device, but the better thermostat device stays not available.

Any idea what to check next?

kind regards