[zha] write to manufacturer-specific cluster fails

1

I’m on version 0.88.0b2.
I try to control an Eurotronic Spirit Zigbee thermostat, and I can already set the temperature. Now I try to set some vendor-specific attributes:

zha.set_zigbee_cluster_attribute

{
  "ieee": "00:00:00:00:00:00:00:00",
  "cluster_id": 513,
  "attribute": 16392,
  "cluster_type": "out",
  "value": 6,
  "endpoint_id": 1
}

But I get the following error message:
Failed to parse message (b'184004b1') on cluster 513, because 177 is not a valid Status

what did I do wrong?
when I use an attribute that is also available in the ZHA panel, everything works fine.

Here is a link to the official manual: https://eurotronic.org/wp-content/uploads/2019/01/Spirit_ZigBee_BAL_web_DE_view_V9.pdf (it’s german, but the cluster definition starting at page 13 is in english)