The request was aborted: Failed to create a secure SSL / TLS channel. even we have all TLS code example

Example: The request was aborted: Could not create SSL/TLS secure channel.

private void Somewhere() {
    ServicePointManager.ServerCertificateValidationCallback += new RemoteCertificateValidationCallback(AlwaysGoodCertificate);
}

private static bool AlwaysGoodCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors policyErrors) {
   return true;
}