DataMember return null

Question

I use SoapUI to test my web service. The point is that is not taking the value of some tag, i.e,

<con:customerLastName>Smith</con:customerLastName> <con:customerFirstName>John</con:customerFirstName>

I don't know reason but alway DataMember customerFirstName return null

My contract.cs

[DataContract]
public class recordParameter
{
  [DataMember(EmitDefaultValue = false)]
  public string customerLastName { get; set; }
  [DataMember(EmitDefaultValue = false)]
  public string customerFirstName { get; set; }
 }

My ws.cs

case "customerData":
     if (!String.IsNullOrEmpty(request.parameters.record.customerLastName) && !String.IsNullOrEmpty(request.parameters.record.customerFirstName)){