RestSharp vs PortableRest (GET / POST)

gistfile1.cs

// POST Working in RestSharp
var client = new RestClient(url);
var request = new RestRequest("/oauth/access_token?client_id=" + clientid + "&client_secret=" + clientsecret, Method.POST);
request.AddParameter("grant_type", "password");
request.AddParameter("username", username);
request.AddParameter("password", password);
client.ExecuteAsync(request, response =>
{
    // Do stuff with the response
});

// GET Working in PortableRest
BaseUrl = url;
var request = new RestRequest("oauth/access_token?client_id=" + clientId + "&client_secret=" + clientSecret, HttpMethod.Get);
request.AddQueryString("username", username);
request.AddQueryString("password", password);
request.AddQueryString("grant_type", "password");
return await ExecuteAsync<Result>(request);


// POST *NOT* Working in PortableRest
// Error: "Index out of range"
BaseUrl = url;
var request = new RestRequest("oauth/access_token?client_id=" + clientId + "&client_secret=" + clientSecret, HttpMethod.Post);
request.AddHeader("Accept", "application/json, text/javascript, */*; q=0.01");
request.AddQueryString("username", username);
request.AddQueryString("password", password);
request.AddQueryString("grant_type", "password");
return await ExecuteAsync<Result>(request);

// POST NOT working in PortableRest
// Error: "Value cannot be NULL, Value: content"
BaseUrl = url;
var request = new RestRequest("oauth/access_token?client_id=" + clientId + "&client_secret=" + clientSecret, HttpMethod.Post);
request.AddParameter("username", username);
request.AddParameter("password", password);
request.AddParameter("grant_type", "password");
return await ExecuteAsync<Result>(request);

I will add these to the PortableRest unit tests and see what happens. Thanks!