Connect to SSL SOAP Host via "Service Reference" and pass Security Header

I am trying to connect to a SSL SOAP service host by C# using Service Reference. This is my request message:

<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:u="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
    <s:Header>
        <VsDebuggerCausalityData xmlns="http://schemas.microsoft.com/vstudio/diagnostics/servicemodelsink">uIDPo/zwMmtdsVhFsAVDkQbiV/4AAAAA1zXtnc72UEm+4tlKzvCxsvN6OC2prvRIljIX4XzHKEYACQAA</VsDebuggerCausalityData>
        <o:Security s:mustUnderstand="1" xmlns:o="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd">
            <u:Timestamp u:Id="_0">
                <u:Created>2016-03-18T12:45:27.558Z</u:Created>
                <u:Expires>2016-03-18T12:50:27.558Z</u:Expires>
            </u:Timestamp>
            <o:UsernameToken u:Id="uuid-2c7986ba-eee5-4411-90a9-a02b625c55ff-1">
                <o:Username>MyUserName</o:Username>
                <o:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">MyPlainPassword</o:Password>
            </o:UsernameToken>
        </o:Security>
    </s:Header>
    <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
        <generateId xmlns="http://com.vedaadvantage/dp3/Enterprise/StandardTradeCreditCommercial/IndividualCommercialService"/>
    </s:Body>
</s:Envelope>

This is the message that my service sends to the host. But the host returns as below:

Security processor was unable to find a security header in the message. This might be because the message is an unsecured fault or because there is a binding mismatch between the communicating parties. This can occur if the service is configured for security and the client is not using security.

This is my config file:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

  <system.serviceModel>

    <bindings>
      <customBinding>
        <binding name="myBinding">
          <textMessageEncoding messageVersion="Soap11" />
          <security  authenticationMode="UserNameOverTransport"
                     messageSecurityVersion="WSSecurity10WSTrust13WSSecureConversation13WSSecurityPolicy12BasicSecurityProfile10" >
          </security>

          <httpsTransport />
        </binding>
      </customBinding>
    </bindings>
    <client>
      <endpoint address="https://{URL}"
        binding="customBinding"
                bindingConfiguration="myBinding"
        contract="ServiceReference2.MyService"
                name="IndividualCommercialService" />
    </client>
  </system.serviceModel>
</configuration>

Although when I send the same XML via SOAPUI or other HTTP Post methods it works fine.

I also extract and attached the certificate and user/pass as below:

private static X509Certificate2 DownloadSslCertificate(string strDNSEntry)
        {

            X509Certificate2 cert = null;
            using (TcpClient client = new TcpClient())
            {
                //ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;           
                client.Connect(strDNSEntry, 443);

                SslStream ssl = new SslStream(client.GetStream(), false, new RemoteCertificateValidationCallback(ValidateServerCertificate), null);
                try
                {
                    ssl.AuthenticateAsClient(strDNSEntry);
                }
                catch (AuthenticationException e)
                {
                    //log.Debug(e.Message);
                    ssl.Close();
                    client.Close();
                    return cert;
                }
                catch (Exception e)
                {
                    //log.Debug(e.Message);
                    ssl.Close();
                    client.Close();
                    return cert;
                }
                cert = new X509Certificate2(ssl.RemoteCertificate);
                ssl.Close();
                client.Close();
                return cert;
            }
        }

        private static void Main(string[] args){
                var proxy = new MyService();

                var uri = proxy.Endpoint.Address.Uri;
                var cer = DownloadSslCertificate(uri.DnsSafeHost);

                EndpointIdentity identity = EndpointIdentity.CreateDnsIdentity(cer.Subject.Replace("CN=", ""));
                EndpointAddress address = new EndpointAddress(proxy.Endpoint.Address.Uri, identity);

                proxy.Endpoint.Address = address;

                proxy.ClientCredentials.UserName.UserName = "MyUserName";
                proxy.ClientCredentials.UserName.Password = "MyPlainPassword";
                proxy.ClientCredentials.ServiceCertificate.DefaultCertificate = cer;

                proxy.HellowWorld();
          }

I am not sure whether the method that I am getting the certificate is correct or not and also why HTTP Post works but my Service Reference Call does not.

Thanks in advance for your help.

Cheers