Cannot create proxy object in WCF

I am using WCF service from this link:

http://www.paymentsgateway.com/developerDocumentation/Integration/webservices/merchantservice.aspx#authentication

Now here if you scroll down this link they have given an eg of how to create a client:

    private void CreateClient(int mid)
{
    ClientRecord client = new ClientRecord();
    client.MerchantID = MerchantID;
    client.FirstName = "Bob";
    client.LastName = "Smith";
    //other code describing client omitted

    try
    {
        using (ClientServiceClient proxy = new ClientServiceClient())
        {
            int id = proxy.createClient(Authenticate.GetClientAuthTicket(txtID.Text.Trim(), txtKey.Text.Trim()), client);
            Response.Write("Created Client ID = " + id.ToString());
        }
    }
    catch (Exception e)
    {
      Response.Write(e.Message);
    }
}

Now I dont understand what is this: ClientServiceClient??? I created the implementation like this:

 public static PaymentsGatewayTest.Authentication GetClientAuthTicket (string APILogin, string key)
    {
        PaymentsGatewayTest.Authentication ticket = new PaymentsGatewayTest.Authentication();
        ticket.APILoginID = APILogin;
        ticket.UTCTime = DateTime.UtcNow.Ticks.ToString();
        ticket.TSHash = GenerateTSHash(ticket.APILoginID + "|" + ticket.UTCTime, key.Trim());
        return ticket;
    }

         private void CreateClient(int mid)
    {
        ClientRecord client = new ClientRecord();
        client.MerchantID = 11245;
        client.FirstName = "Bob";
        client.LastName = "Smith";
        //other code describing client omitted

        try
        {
            using (PaymentsAuthClient proxy = new PaymentsAuthClient())
            {

                int id = proxy.createClient(Authenticate.GetClientAuthTicket("", "", client));
                //Response.Write("Created Client ID = " + id.ToString());
            }
        }
        catch (Exception e)
        {
            //Response.Write(e.Message);
        }
    }

I have create a Singleton class called PaymentsAuthClient, but this does not seems to work. What I am doing wrong here???

Thank you for your help in adv :)