Authorize takes forever with password flow

Thanks, call log work perfect but when i want to send sms like

static async Task Main(string[] args)
{
    using (var rc = await Login())     {         await SendSms(rc);     } }
private static async Task<RestClient> Login()
{
    var rc = new RestClient("***", "*********", "https://platform.devtest.ringcentral.com/");
    await rc.Authorize("+*****", "101", "*****");
    return rc;
} public static async Task SendSms(RestClient rc)
{
    var sms = new CreateSMSMessage()
    {
        @from = new MessageStoreCallerInfoRequest() { phoneNumber = "+****" },
        to = new[] { new MessageStoreCallerInfoRequest() { phoneNumber = "+****" }, },
        text = "test yaacov"
    };
     var resTask = await rc.Restapi().Account().Extension("101").Sms().Post(sms);
} 

The Authorize return token but post sms get exception 

System.ObjectDisposedException: 'Cannot access a disposed object.
Object name: 'System.Net.Http.StringContent'.'

When i run same details with Api reference "try it out" button it work fine