Error in Person.update

[nik]

{"method":"Person.update","params":{"Person":{"id":0,"firstName":"Frans","lastName":"Van Assche"}},"jsonrpc":"2.0","id":"req-002"} {"returnCode":7,"error":"Expected a ',' or '}' at 52 [character 53 line 1]"} {"id":"req-002","jsonrpc":"2.0","error":{"code":-32602, "message": "schema violations in params: {$.Person.familyName: is missing and it is not optional - $.Person.givenName: is missing and it is not optional - }"}}

ERROR in Person.update: results do not match!!!