WP8 Sending JSON to Server

WP8 Sending JSON to Server

I am trying to POST some JSON data to my Server. I am using simple code
which I have attained from: Http Post for Windows Phone 8
Code:
string url = "myserver.com/path/to/my/post";
// HTTP web request
var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
httpWebRequest.ContentType = "text/plain; charset=utf-8";
httpWebRequest.Method = "POST";
// Write the request Asynchronously
using (var stream = await
Task.Factory.FromAsync<Stream>(httpWebRequest.BeginGetRequestStream,
httpWebRequest.EndGetRequestStream,
null))
{
//create some json string
string json = "{ \"my\" : \"json\" }";
// convert json to byte array
byte[] jsonAsBytes = Encoding.UTF8.GetBytes(json);
// Write the bytes to the stream
await stream.WriteAsync(jsonAsBytes, 0, jsonAsBytes.Length);
}
I am getting an error though on await and Task:

Anyone see the obvious error?