Create XlangMessage using C# helper (InvalidOperationException error)

Hi,

Iam trying to create a Multipart message which contains a Body and multiple parts.  I receive a email message and use a multipart type message to receive the email.

Then I send the received MP message to the function CreateMPResMsg.
By looping through the multipart, I try to access its properties and create a multipart message. The problem I am facing is while I am trying to send this message using a send port, Iam getting the Exception InvalidOperationException.
Inner exception: Microsoft.XLANGs.Core.PartWrapperForUserCode cannot be serialized because it does not have a parameterless constructor.

Please point me to the right direction or provide some link to sample code to achieve this.

Thanks,
GRD

Code:
public static XLANGMessage CreateMPResMsg(XLANGMessage MPRecdEmail)
        {
            int iCount = 0;
            string sFileName;

            BTXMessage btxMsg = new BTSInternalMsg(“MPMessage”, Service.RootService.XlangStore.OwningContext);
            btxMsg.AddPart(“”, “Body”);
       
            XLANGMessage MpMsg = btxMsg.GetMessageWrapperForUserCode();

            iCount = MPRecdEmail.Count;

            for (int iLoop = 0; iLoop < iCount; iLoop++)
            {
           
                object oTemp = MPRecdEmail[iLoop].GetPartProperty(typeof(global::MIME.FileName));

                if (oTemp != null)
                {
                    sFileName = oTemp.ToString();
                }
                else
                {
                    sFileName = iLoop.ToString() + “_” + MPRecdEmail[iLoop].Name;
                }

                AddXlangMsgPart(MpMsg, MPRecdEmail[iLoop], sFileName);
            }
            return MpMsg;
        }

 public static void AddXlangMsgPart(XLANGMessage msg, object part, String partName)
            {
                if (msg == null)
                    throw new ArgumentNullException(“message”);
                if (part == null)
                    throw new ArgumentNullException(“part null”);
                if (partName == null)
                    throw new ArgumentNullException(“partName”);
                msg.AddPart(part, partName);
               }

 Error Details:

Event Type: Error
Event Source: XLANG/s
Event Category: None
Event ID: 10034
Date:  4/15/2008
Time:  6:46:06 PM
User:  N/A
Computer: BzDevPc
Description:
Uncaught exception (see the ‘inner exception’ below) has suspended an instance of service ‘Multipart.Learn.Multipart(d10bbd8a-c895-065c-c540-8462515c6aa4)’.
The service instance will remain suspended until administratively resumed or terminated.
If resumed the instance will continue from its last persisted state and may re-throw the same unexpected exception.
InstanceId: 8aca4bae-90d5-4acc-a731-50a635802694
Shape name: send MPMsg Created by code
ShapeId: 242e0994-7e2f-4838-862e-83bf99d1853f
Exception thrown from: segment 1, progress 43
Inner exception: Microsoft.XLANGs.Core.PartWrapperForUserCode cannot be serialized because it does not have a parameterless constructor.
       
Exception type: InvalidOperationException
Source: System.Xml
Target Site: Void CheckSupported()
The following is a stack trace that identifies the location where the exception occured
   at System.Xml.Serialization.TypeDesc.CheckSupported()
   at System.Xml.Serialization.TypeScope.GetTypeDesc(Type type, MemberInfo source, Boolean directReference, Boolean throwOnError)
   at System.Xml.Serialization.ModelScope.GetTypeModel(Type type, Boolean directReference)
   at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(Type type, XmlRootAttribute root, String defaultNamespace)
   at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)
   at System.Xml.Serialization.XmlSerializer..ctor(Type type)
   at Microsoft.XLANGs.RuntimeTypes.DotNetTypeMetadata.GetXmlSerializer()
   at Microsoft.XLANGs.RuntimeTypes.XmlHelpers.StreamFromObject(Object o, Type t)
   at Microsoft.XLANGs.Core.Value.GetResetableStream(String& encoding, Boolean wantEncoding)
   at Microsoft.XLANGs.Core.Part.Persist(String& encoding, Boolean wantEncoding)
   at Microsoft.BizTalk.XLANGs.BTXEngine.BTXXlangStore.StagePartData(Part part)
   at Microsoft.BizTalk.XLANGs.BTXEngine.BTXXlangStore.PrepareMessage(XLANGMessage msg, IList promoteProps, IList toPromote)
   at Microsoft.BizTalk.XLANGs.BTXEngine.BTXXlangStore.WriteMessageState(IBTPEPInfoLookup pepLookup, Guid portId, XLANGMessage msg, Segment seg, String opname, String url, IList promoteProps, Boolean track, IList toPromote)
   at Microsoft.BizTalk.XLANGs.BTXEngine.BTXLogicalPortBinding.SendMessage(XLANGMessage msg, XlangStore store, Segment seg, OperationInfo op, IList additionalProps, IList toPromote, Boolean ignoreRoutingFailure)
   at Microsoft.BizTalk.XLANGs.BTXEngine.BTXPortBase.SendMessage(Int32 iOperation, XLANGMessage msg, Correlation[] initCorrelations, Correlation[] followCorrelations, Context cxt, Segment seg, ActivityFlags flags)
   at Multipart.Learn.Multipart.segment1(StopConditions stopOn)
   at Microsoft.XLANGs.Core.SegmentScheduler.RunASegment(Segment s, StopConditions stopCond, Exception& exp)