Serialization XML SOAP .NET

[hic78]

Hi,

I use a proxy class to invoke web service developed in SOAP/Java:

using System.Diagnost ics;
using System.Xml.Seri alization;
using System;
using System.Web.Serv ices.Protocols;
using System.Componen tModel;
using System.Web.Serv ices;

namespace PSA.Cfg.CfgPage s.Classes.Confi guratorClient
{
public class Flow : SoapHeader
{
public string Process;
}

/// <remarks/>
[System.Diagnost ics.DebuggerSte pThroughAttribu te()]
[System.Componen tModel.Designer CategoryAttribu te("code")]
[System.Web.Serv ices.WebService BindingAttribut e(Name="cc", Namespace="cc:C arConfigurator" )]
public class ConfigClient : System.Web.Serv ices.Protocols. SoapHttpClientP rotocol
{
/// Constructeur pour ne pas aller dans le web.config <remarks/>
public ConfigClient(st ring carConfigConnec tion)
{
this.Url = carConfigConnec tion;
}

/// <remarks/>
[System.Web.Serv ices.Protocols. SoapDocumentMet hodAttribute("" , RequestNamespac e="cc:CarConfig urator", ResponseNamespa ce="cc:CarConfi gurator", Use=System.Web. Services.Descri ption.SoapBindi ngUse.Encoded, ParameterStyle= System.Web.Serv ices.Protocols. SoapParameterSt yle.Wrapped)]
[return: System.Xml.Seri alization.SoapE lementAttribute ("return")]

public string config(string Request)
{
object[] results = this.Invoke("co nfig", new object[] {Request});
//Ajout Trace
return ((string)(resul ts[0]));
}
}

Sometimes I have this error message :

Erreur application : System.InvalidO perationExcepti on;There is an error in XML document (5, 2).; at System.Xml.Seri alization.XmlSe rializer.Deseri alize(XmlReader xmlReader, String encodingStyle, XmlDeserializat ionEvents events)
at System.Xml.Seri alization.XmlSe rializer.Deseri alize(XmlReader xmlReader, XmlDeserializat ionEvents events)
at System.Xml.Seri alization.XmlSe rializer.Deseri alize(XmlReader xmlReader)
at System.Web.Serv ices.Protocols. SoapHttpClientP rotocol.ReadRes ponse(SoapClien tMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
at System.Web.Serv ices.Protocols. SoapHttpClientP rotocol.Invoke( String methodName, Object[] parameters)
at PSA.Cfg.CfgPage s.Classes.Confi guratorClient.C onfigClient.con fig(String Request)

It occurs from time to time, it is really random
My application is installed on a farm of 4 servers

Thank you in advance for your assistance
Best regards