Access All Custom Fields on a MAPI folder

Question

I am trying to export data in a Microsoft Exchange 2003 public folder. However, I can not seem to retrieve the list of all non-standard/custom fields in the folder. When I try MAPIFolder.UserDefinedProperties I get an empty list. I have tried the following code, but it gives me some (not all) of the custom fields.

        var document = new XDocument();
        var contacts = new XElement("Contacts");

        // create an instance of the Outlook Application
        var outlook = new Microsoft.Office.Interop.Outlook.Application();

        // get the namespace
        var space = outlook.GetNamespace("MAPI");

        // set folder location
        var folder = space.Folders["Public Folders"]
                        .Folders["All Public Folders"]
                        .Folders["Our Company"]
                        .Folders["Contacts Databases"]
                        .Folders["Equipment Database"];

        // Retrieve custom fields
        // var properties = folder.UserDefinedProperties;

        // Retrieve the current view
        var view = XDocument.Parse(folder.CurrentView.XML);
        int i = 0;
        foreach (Microsoft.Office.Interop.Outlook.ContactItem item in folder.Items)
        {
            // create a new contact node
            var contact = new XElement("Contact");
            // get a reference to this item's property accessor
            var access = item.PropertyAccessor;

            // add the standard ContactItem fields
            contact.Add(new XElement("LastName", item.LastName));
            contact.Add(new XElement("FirstName", item.FirstName));
            contact.Add(new XElement("Company", item.CompanyName));
            contact.Add(new XElement("BusinessPhone", item.BusinessTelephoneNumber));
            contact.Add(new XElement("HomePhone", item.HomeTelephoneNumber));
            contact.Add(new XElement("Email", item.Email1Address));

            // add the custom fields
            foreach (var element in view.Descendants("column").Skip(3))
            {
                contact.Add(new XElement("column",
                    new XAttribute("heading", element.Element("heading").Value),
                    access.GetProperty(element.Element("prop").Value)));
            }
            contacts.Add(contact);
            i++;
        }

        //var table = folder.GetTable(null, null);
        //var columns = table.Columns;
        //while (!table.EndOfTable)
        //{
        //    var contact = new XElement("contact");
        //    var row = table.GetNextRow();
        //    for(int j = 1; j <= columns.Count; j++){
        //        string name = columns[j].Name;
        //        contact.Add(new XElement(name, row[name]));
        //    }
        //    contacts.Add(contact);
        //    i++;
        //}

        contacts.Add(new XAttribute("count", i));

        document.Add(contacts);

Please help in whatever way possible.