C# Service Request -

i stack on apple gsx api request in c# project. ok cannot response api.
certificates done, static ips have whitelisted.

return error when request "https://gsxapiut.apple.com/gsx-ws/services/emea/asp"

{"an error occurred while making http request https://gsxapiut.apple.com/gsx-ws/services/emea/asp. due fact server certificate not configured http.sys in https case. caused mismatch of security binding between client , server."}

request function :

 public void authenticate()     {         try         {             basichttpbinding binding = new basichttpbinding(basichttpsecuritymode.transport);             binding.security.transport.clientcredentialtype = httpclientcredentialtype.certificate;                            endpointaddress endpoint = new endpointaddress("https://gsxapiut.apple.com/gsx-ws/services/emea/asp");                            var sslcertfilename = "test.p12";             var sslcertpassword ="xxxxx";             gsxapi3.gsxwsemeaaspportclient service = new gsxapi3.gsxwsemeaaspportclient();              servicepointmanager.expect100continue = true;             servicepointmanager.securityprotocol = securityprotocoltype.ssl3;             service.clientcredentials.clientcertificate.certificate = new x509certificate2(                sslcertfilename,                 sslcertpassword, x509keystorageflags.machinekeyset);              var auth = new gsxapi3.authenticaterequesttype()             {                 languagecode = "en",                 serviceaccountno = "xxxxxxxxx",                 userid = "xxxxxxxxxxx",                 usertimezone = "cet"             };              var session = service.authenticate(auth);                             var usersessionid = new gsxapi3.gsxusersessiontype { usersessionid = session.usersessionid };         }         catch (exception err)         {           }       }