Web service security using X509 certificate in Classic ASP - wcf

Question

I'm trying to call a C# dll from classic ASP - this dll calls a webservice. I've been asked by someone that runs that ASP site to create this dll for him and had tons of problems doing that. He told me he has a *.crt file, and that the dll should use that to call his SSL-based webservice.
So since this is classic ASP, had to make it a COM object and also configure the service and endpoint through code, like so:
BasicHttpBinding binding = new BasicHttpBinding();
binding.Name = "Service1Binding";
binding.CloseTimeout = System.TimeSpan.Parse("00:01:00");
binding.OpenTimeout = System.TimeSpan.Parse("00:01:00");
binding.ReceiveTimeout = System.TimeSpan.Parse("00:10:00");
binding.SendTimeout = System.TimeSpan.Parse("00:01:00");
binding.AllowCookies = false;
binding.BypassProxyOnLocal = false;
binding.HostNameComparisonMode = System.ServiceModel.HostNameComparisonMode.StrongWildcard;
binding.MaxBufferSize = 65536;
binding.MaxBufferPoolSize = 524288;
binding.MaxReceivedMessageSize = 65536;
binding.MessageEncoding = System.ServiceModel.WSMessageEncoding.Text;
binding.TextEncoding = System.Text.Encoding.UTF8;
binding.TransferMode = System.ServiceModel.TransferMode.Buffered;
binding.UseDefaultWebProxy = true;
binding.ReaderQuotas.MaxDepth = 32;
binding.ReaderQuotas.MaxStringContentLength = 8192;
binding.ReaderQuotas.MaxArrayLength = 16384;
binding.ReaderQuotas.MaxBytesPerRead = 4096;
binding.ReaderQuotas.MaxNameTableCharCount = 16384;
binding.Security.Mode = System.ServiceModel.BasicHttpSecurityMode.None;
binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None;
binding.Security.Transport.ProxyCredentialType = HttpProxyCredentialType.None;
binding.Security.Transport.Realm = "";
binding.Security.Mode = BasicHttpSecurityMode.TransportWithMessageCredential;
binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Certificate;
binding.Security.Message.ClientCredentialType = BasicHttpMessageCredentialType.Certificate;
binding.Security.Message.AlgorithmSuite = System.ServiceModel.Security.SecurityAlgorithmSuite.Default;
EndpointAddress endpoint =
new EndpointAddress("https://webservice.XXXX.com/Service1.svc");
var cert = new X509Certificate2(certPath); //local path to *.crt file
Service1.ServiceClient client = new Service1.ServiceClient(binding, endpoint);
client.ClientCredentials.ClientCertificate.Certificate = cert;
var result = client.HelloWorld();
At first i got a Forbidden exception, so I changed the Security.Mode to be BasicHttpSecurityMode.TransportWithMessageCredential. Now, I'm getting this error:
The private key is not present in the X.509 certificate
Is it looking for the cert in the store, or using the path I gave it? How can i make this work?