PropertyBag Problem

The Error Message is this:
System.Web.Services.Protocols.SoapException: Server was unable to process request.
System.Runtime.InteropServices.COMException(0X800A0062): Exception from HRESULT: 0X800A0062.

We have problem in our web service project using Visual C#.NET. The system is designed to call the PropBagClass which is a Visual Basic DLL. If our reference is the compiled web service dll, the error appears. But if we make our reference the uncompiled one, it works. How can we fixed it? Can anyone help us? Thanks.

By the way, these are the part of the codes that have an error..

[WebMethod]
public void Order(OrderBEC order, OrderDetailDEC[] details)
{
OrderControllerClass orderController;
PropertyBagClass ordersPropBag;
PropertyBagClass detailPropBag;

string orderHeader;
string[] orderdetails;
int detailIndex = 0;

try
{
ordersPropBag = new PropertyBagClass(); .................
.........................................