add key failed

 --> POST https://domofon.dom38.ru/api/contracts/addkey http/1.1
 Content-Type: application/x-www-form-urlencoded
 Content-Length: 50
 number=BB54C519&contracts=57dbd1b1c2bb0120679d0d56
 --> END POST (50-byte body)
 <-- 200 OK https://domofon.dom38.ru/api/contracts/addkey (544ms)
 Date: Sun, 20 May 2018 14:57:28 GMT
 Server: Apache/2.4.10 (Ubuntu)
 X-Powered-By: Express
 Access-Control-Allow-Origin: *
 Access-Control-Allow-Methods: GET, POST, OPTIONS, PUT, PATCH, DELETE
 Access-Control-Allow-Headers: X-Requested-With,Content-Type,Authorization,Access-Control-Allow-Headers
 Access-Control-Allow-Credentials: true
 Content-Type: application/json; charset=utf-8
 Content-Length: 212
 ETag: W/"d4-bmqm5NRbpExRGOA2cbpc5AzDTgg"
 Vary: Accept-Encoding
 set-cookie: connect.sid=s%3AhrV0haCcxQ2MzOvCY7HUDgeGvYSPg3xL.yDezvljpG2Y8CLR6gbYUKa%2BoFP3sdCEJTBHPDU5WIg4; Path=/; HttpOnly
 Via: 1.1 domofon.dom38.ru (Apache/2.4.10)
 Keep-Alive: timeout=5, max=100
 Connection: Keep-Alive
 {"number":"BB54C519","attached":true,"removed":false,"isPaidUp":false,"_id":"5a2a492248fbf897762808d3","contracts":[],"errors":["Ключ BB54C519 принадлежит другому пользователю"]}
 <-- END HTTP (212-byte body)