DevDefined - call getInvestmentPositions

//using DevDefined.OAuth.Consumer;
//using DevDefined.OAuth.Framework;

string consumerKey = "<<ConsumerKey>";
string consumerSecret = "<<ConsumerSecret>>";
string accessToken = "<<AccessToken>>";
string accessTokenSecret = "<<AccessTokenSecret>>";
long accountId = <<AccountID>>;

OAuthConsumerContext consumerContext = new OAuthConsumerContext
{
    ConsumerKey = consumerKey,
    ConsumerSecret = consumerSecret,
    SignatureMethod = SignatureMethod.HmacSha1,
    UseHeaderForOAuthParameters = true
};

OAuthSession oSession = new OAuthSession(consumerContext)
                            {
                                AccessToken = new TokenBase
                                                    {
                                                        Token = accessToken,
                                                        ConsumerKey = consumerSecret,
                                                        TokenSecret = accessTokenSecret
                                                    }
                            };

IConsumerRequest consumerRequest = oSession.Request();
consumerRequest = consumerRequest.Get();
consumerRequest = consumerRequest.ForUrl("https://<IPPGatewayBaseUrl>/v1/accounts/" + accountId + "/positions");
consumerRequest = consumerRequest.SignWithToken();

string serviceResponse = consumerRequest.ReadBody();