AMI WebSocket no response

With Asterisk 11.5 I get no response via WebSocket.
The connection could be established and the CLI shows that I’m connected, but when I send the login action or any other, I get no response and the CLI in verbose mode 10 doesn’t show the request.

I init the connection with the protocol ‘sip’ var conn = new WebSocket('ws://', 'sip')

the action packet looks like this

var loginAction = "Action: Login\n\r Username: foo\n\r Secret: bar\r\n \r\n"

When I access AMI via I can do all the Manager stuff and the CLI shows messages when I login.

When I access the AMI via WebSocket, the CLI shows, that a WebSocket-connection is accepted and I can send strings with conn.send(loginAction) but I dont get any response.

Please ask, if you need more details.