Bad request when assigning workspace to the capacity

Hello,

I created the new capacity using rest apis. 
And now I want to assigned trial capacity to this using also rest apis:

POST https://api.powerbi.com/v1.0/myorg/groups/{{targetGroupId}}/AssignToCapacity
Authorization: Bearer {{$aadV2Token appOnly}}
Content-Type: application/json; charset=utf-8

{
  "capacityId": "{{targetCapacityId}}"
}

and getting:

HTTP/1.1 400 Bad Request
Cache-Control: no-store, must-revalidate, no-cache
Pragma: no-cache
Transfer-Encoding: chunked
Content-Type: application/json; charset=utf-8
Strict-Transport-Security: max-age=31536000; includeSubDomains
X-Frame-Options: deny
X-Content-Type-Options: nosniff
RequestId: 52c77ca8-619c-4c1d-b4a2-91945b9b2cf3
Access-Control-Expose-Headers: RequestId
request-redirected: true
home-cluster-uri: https://wabi-us-central-b-primary-redirect.analysis.windows.net/
Date: Wed, 04 Mar 2026 13:57:29 GMT
Connection: close

{
  "error": {
    "code": "CapacityNotInActiveState",
    "pbi.error": {
      "code": "CapacityNotInActiveState"
    }
  }
}

anybody did this making? Maybe trial is not available?

Best,
Jacek