Update Unified Presence not working for other extension

We use the function "Update Unified Presence". This works fine for the own extension. But when specifying another extension we get an error:

Content: {"errors":[{"errorCode":"PRS-012","message":"Presence may be updated for the requester own extension only."}]}

Note: The user we use is a "super admin". So there should be no problem with the permission.

Does anyone know what the problem is and how we can resolve it?