AddBody Post Request from c# in vb

Question

using RestRequest from RestSharp to add a body in a Post request it is:

var request = new RestRequest("somePath", Method.Post)
request.AddBody(new { Something = somethingData});

Now my question is, how can I do this in visual basic .net, I have something like this, but it doesn't work:

Dim request As WebRequest = WebRequest.Create("somePath")
request.Method = "POST"

Dim byteData() As Byte = UTF8.Encoding.UTF8.GetBytes(data.ToString)

request.ContentLength = byteData.Length

Dim postStream As Stream = request.GetRequestStream()
postStream.Write(byteData, 0, byteData.Length)
postStream.Close()

Dim dataStream As Stream = request.GetResponse.GetResponseStream()

Dim sr As New StreamReader(dataStream)
Return sr.ReadToEnd

The solution I find to post using VB is by getting a stream to the request, and passing data, but it doesn't work.

Any help is welcome. Thanks