RestSharp on Windows Phone no set-cookie in response - windows-phone-7

Question

I have a problem with using the RestSharp client on the Windows Phone device. Starting form the beginning, I have the ASP.NET Web Api service hosted online. I have a request user address: POST: http://my-service-url.com/token where I send Email and Password as a body parameters and I get 201 status code and a cookie in the response. When I do it in fiddler everything works fine. I also have the functional test for my API which is using the RestSharp which is also working correctly:
[Given(#"I fill email and password with correct data and I click log in button")]
public void GivenIFillEmailAndPasswordWithCorrectDataAndIClickLogInButton()
{
//Delete user if he exists
_testUserHelper.DeleteTestUser(TestEmail);
//Create new activated user
Assert.IsTrue(_testUserHelper.CreateTestUser(TestEmail, TestPassword));
//Prepare client
var client = new RestClient(CarRentalsConstants.HostAddress);
var restRequest = new RestRequest("api/token", Method.POST) { RequestFormat = DataFormat.Json };
//Add parameters to request
restRequest.AddBody(new { Email = TestEmail, Password = TestPassword });
//Perform request
_response = client.Execute(restRequest);
}
[When(#"the log in login process finishes")]
public void WhenTheLogInLoginProcessFinishes()
{
Assert.AreEqual(HttpStatusCode.Created, _response.StatusCode, _response.Content);
Assert.IsNotNull(_response.Cookies.SingleOrDefault(q => q.Name == ".ASPXAUTH"););
}
The one above works properly, and the cookie is in the response object.
Now what I try to do on my windows phone looks like this:
var restRequest = new RestRequest("token", Method.POST) {RequestFormat = DataFormat.Json};
restRequest.AddBody(new {Email = email, Password = password});
myWebClient.ExecuteAsync(restRequest, (restResponse, handle) =>
{
switch (restResponse.StatusCode)
{
case HttpStatusCode.Created:
{
var cookie = restResponse.Cookies.SingleOrDefault(q => q.Name == ".ASPXAUTH");
successLogicDelegate(cookie);
}
break;
case HttpStatusCode.BadRequest:
{
HandleBadRequest(restResponse.Content, failureLogicDelegate);
}
break;
default:
msgBox.Show(StringResources.ServerConnectionError);
failureLogicDelegate(null);
break;
}
});
And in this case, the response returns the "Created" status code, but the cookie is then set to null. I have no idea what is happening here, but I am fairly certain that server is sending this cookie, so where does it get lost?
Any help will be really appreciated.