以下应该可以帮助您识别问题，这里有两种测试 SSL 连接性的方法，一种是测试站点，另一种是回调方法来确定 SSL 失败的原因.如果不出意外，它应该能让您更好地了解失败的原因.

The following should help you identify the issue, here are two methods to test SSL connectivity one tests the site whilst the other is a callback method to identify why SSL failed. If nothing else it should give you a better idea why it is failing.

当该方法被调用时，它会弹出选择证书对话框，显然当你真正这样做时，你会想要自动从证书存储中读取.我把这个放在里面的原因是因为如果没有找到有效的证书，那么你就会知道你的问题出在证书的安装方式上.

When the method is called it will pop up with the select certificate dialog box, obviously when you do this for real you'll want to read from the cert store automatically. The reason I have put this in is because if no valid certificate is found then you will know your problem is with the way the certificate is installed.

***的办法是将此代码放在一个简单的控制台应用程序中:

The best thing to do is put this code in a simple console app:

using System.Security.Cryptography.X509Certificates;
using System.Net.Security;
using System.Net;

private static void CheckSite(string url, string method)
{
    X509Certificate2 cert = null;
    ServicePointManager.ServerCertificateValidationCallback += ValidateRemoteCertificate;

    X509Store store = new X509Store(StoreLocation.LocalMachine);
    store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);
    X509Certificate2Collection certcollection = (X509Certificate2Collection)store.Certificates;
    // pick a certificate from the store
    cert = X509Certificate2UI.SelectFromCollection(certcollection, 
            "Caption",
            "Message", X509SelectionFlag.SingleSelection)[0];

    store.Close();

    HttpWebRequest ws = (HttpWebRequest)WebRequest.Create(url);
    ws.Credentials = CredentialCache.DefaultCredentials;
    ws.Method = method;
    if (cert != null)
        ws.ClientCertificates.Add(cert);

    using (HttpWebResponse webResponse = (HttpWebResponse)ws.GetResponse())
    {
        using (Stream responseStream = webResponse.GetResponseStream())
        {
            using (StreamReader responseStreamReader = new StreamReader(responseStream, true))
            {
                string response = responseStreamReader.ReadToEnd();
                Console.WriteLine(response);
                responseStreamReader.Close();
            }

            responseStream.Close();
        }
        webResponse.Close();
    }
}

/// <summary>
/// Certificate validation callback.
/// </summary>
private static bool ValidateRemoteCertificate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors error)
{
    // If the certificate is a valid, signed certificate, return true.
    if (error == System.Net.Security.SslPolicyErrors.None)
    {
        return true;
    }

    Console.WriteLine("X509Certificate [{0}] Policy Error: '{1}'",
        cert.Subject,
        error.ToString());

    return false;
}