unable to ignore certificate check #3

I am in the development of creating a client app to connect to web socket server in windows 7 environment both ws and wss, and I'd like to ignore the certificate check during development.

following code works, with System.Net.WebSockets.ClientWebSocket
System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

however when using System.Net.WebSockets.Manage.ClientWebSocket, its doesn't work and couldn't connect to websocket server.

Any extra configuration has to be done in this managed version?