openAuth protocol error

{"The remote server returned an error: (400) Bad Request."}

at System.Net.HttpWebRequest.GetResponse() at DotNetOpenAuth.Messaging.StandardWebRequestHandler.GetResponse(HttpWebRequest request, DirectWebRequestOptions options) in c:\BuildAgent\work\a02b428f36957bca\src\DotNetOpenAuth\Messaging\StandardWebRequestHandler.cs:line 126

    public static readonly ServiceProviderDescription ServiceDescription = new  ServiceProviderDescription
{
    RequestTokenEndpoint = 
       new MessageReceivingEndpoint("https://www.google.com/account/OAuthGetRequestToken", HttpDeliveryMethods.AuthorizationHeaderRequest | HttpDeliveryMethods.GetRequest),
    UserAuthorizationEndpoint = 
       new MessageReceivingEndpoint("https://www.google.com/accounts/OAuthAuthorizeToken",
HttpDeliveryMethods.AuthorizationHeaderRequest | HttpDeliveryMethods.GetRequest),
    AccessTokenEndpoint = 
       new MessageReceivingEndpoint("https://www.google.com/accounts/OAuthGetAccessToken", HttpDeliveryMethods.AuthorizationHeaderRequest | HttpDeliveryMethods.GetRequest),
    TamperProtectionElements = 
       new ITamperProtectionChannelBindingElement[] { new HmacSha1SigningBindingElement() },
  };



public void StartOAuth()
{
    var consumer = new WebConsumer(GoogleConsumer.ServiceDescription, new InMemoryTokenManager("user", "pass"));
 // Url to redirect to
    var authUrl = new Uri("http://www.google.com");
 // request access
    consumer.Channel.Send(consumer.PrepareRequestUserAuthorization(authUrl, null, null));

      throw new NoRedirectToAuthPageException();
     }