Sending to a custom webservice

Hi

I have a simple webservice, I have a simple orchestration, getfile, send
to 
ws, get response from ws, send resp to file ****t.

I can generate a schema, drop into the "in file" drop and see a response 
appear in the "out folder".  The problem comes if I simulate missing a
value 
in a node, my ws throws a soap exception .

ie.

I pass

<ns0:ApprovedLimit/> instead of
<ns0:ApprovedLimit>0</ns0:ApprovedLimit>

the web service generates a soap exception, I can create a simple c# 
consumer as pass the same parameters except the ApprovedLimit and no error

Any thoughts? Is there something I'm missing in my webservice? OR do I
need 
to ensure the message is complete in my orch before sending ?

Thanks for your time.

using System;
using System.Data;
using System.Web;
using System.Collections;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.ComponentModel;
using System.Xml;
namespace CRM_ProxyWebService
{
/// <summary>
/// Summary description for AService
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ToolboxItem(false)]
public class AService : System.Web.Services.WebService
{
public class RequestMessage
{
public string CompanyKey = string.Empty; // CPTY_key
public string CompanyName = string.Empty; // CPTY_Name
public string DBNumber= string.Empty; //DB_NUMBER
public string CreditScore = string.Empty; //CPTY_SCORE
public float ApprovedLimit;// = string.Empty; // APPROVED_LIMIT
public float SuggestedLimit;// = string.Empty; // SUGGESTED_LIMIT

etc.....
}
public class ResponseMessage
{
// return OK, MANYKEYS, CRMFAILED
public string StatusMessage = string.Empty;
public string ExceptionText = string.Empty;
}
[WebMethod]
public ResponseMessage ProcessCrm(RequestMessage requestMessage)
{
ResponseMessage responseMessage = new ResponseMessage();
try
{
CrmLog.LogFile("Started....");
responseMessage.StatusMessage = "OK";
CrmLog.LogFile("Stopped....");
}
catch (Exception ex)
{
responseMessage.ExceptionText = ex.Message.ToString();
CrmLog.LogFile(ex.Message.ToString());
}
return responseMessage;
}
}
}