Error creating users

[tillre]

I'm getting the following error when trying to create a new user:

{ "error": "forbidden", "reason": "Doc ID must be of the form org.couchdb.user:name", "status": 403, "name": "forbidden", "message": "Doc ID must be of the form org.couchdb.user:name", "docId": "org.couchdb.user:till-operator2" }