Virtual Thermostat2 can't add device

Hello I have been using my Danfoss LC-13 thermostats with the older zipato version.

I had made heating shedules, and it worked quite fine. I now have switched to the new zipato app, and am currently setting everything up.

So I have been able to add all my devices, and I now want to set up the heating shedules for my thermostats again.

As far as I understand, I have to set up a "virtual thermostat" for this. So I did the following:

1. I went to "devices"

2. I choose "Virtual Server"

3. I click on the "+" Button

4. I choose "thermostat zone"

5. Give it a name and then choose the thermostat from the drop down list.

6. It tries to add device and then gives me the message "Thermostat device(s) could not be added".

It also tells me that "You can add same devices later. Continue?"

7. As no other option is given, I click on "OK".

8. After that it tells me "syncronisation successful"

9. After that I am in the menue of the virtual thermostat and I click on "devices/Inputs/outputs"

10. I try to add the thermostat under the "thermostat devices" menu. but it gives me the "RuntimeException." message and nothing happens.

I hope someone can help. Thanks in advance