HTTP Proxy with Socket

In the newesst version:

socket.HttpProxyHostname = "127.0.0.1"; socket.HttpProxyPort = 8888;

//it doesn't works; (when fiddler is the proxyserver at 9.5.0.56 version)

socket.SocksHostname = "127.0.0.1"; socket.SocksPort = 1080; socket.SocksVersion = 5;

//it works; (ccproxy server is the proxyserver at 9.5.0.56 version)

In the 9.3.2 version above code all works well;

why? how to solve this problems,it is important to my program;