I'm getting the follow message when I try to call a routine which creates an
instance of my class TG.ADO.DataConnector.ADOConnectorColumn.

The calling code is

                //
                try {Inquire();}
                catch (Exception ex)
                {
                    System.Diagnostics.Debug.WriteLine(ex.Message);
                }
                catch {}

The runtime error is

Derived method GetObjectData in type TG.ADO.DataConnector.ADOConnectorColumn
from assembly TG.ADO, Version=4.3.13.1, Culture=neutral,
PublicKeyToken=d6af0e7fcb70d177 can not reduce access.

The Inquire() method is

        public override bool Inquire()
        {
                bool bNeedToOpen = (_adoConn == null);

                ADODB.Recordset rs = null;
                try
                {
                    // OleDbConnection
                    if (bNeedToOpen)
                    {
                        //                    // Skip if couldn't open the file.
                        _adoConn = ADOHelper.OpenConnection(ConnectionString,
ADODB.ConnectOptionEnum.adConnectUnspecified);
                        if (_adoConn == null)
                            return false;
                    }

                    // Get a recordset from the table
                    Object RecordsAffected = null;
                    string cmdStr = String.Format(@"select * from {0}", _Name);
                    rs = _adoConn.Execute(cmdStr, out RecordsAffected, (int)
ADODB.CommandTypeEnum.adCmdText);

                    // Clear the schema information
                    Schema.Clear();

                    // Loop over the fields and update the summary information.
                    StringCollection fields = new StringCollection();
                    foreach (ADODB.Field field in rs.Fields)
                    {
                        fields.Add(field.Name);

                        // Add the field to the schema
                        TG.Data.DataColumn dc = new ADOConnectorColumn(field);
                       
                        Schema.Columns.Add(dc);
                    }
                   
                    _SummaryInfo["Columns"] = fields;
                }
                catch {}
                finally
                {
                    if (rs != null)
                        rs.Close();

                    // Close if needed
                    if (bNeedToOpen)
                    {
                        _adoConn.Close();
                        _adoConn = null;
                    }
                }

            return true;
  }

but the first line of the method isn't being reached (i.e. the runtime is
throwing the exception before invoking the method).

The ADOConnectorColumn class is a C# class defined as

using System;
using System.Collections;
using System.ComponentModel;
using System.Runtime.Serialization;

using TG.Core;
using TG.Data;

namespace TG.ADO.DataConnector
{
    /// <summary>
    /// Summary description for ADOConnectorColumn.
    /// </summary>
    [Serializable]
    public class ADOConnectorColumn : TG.Data.DataColumn, ISerializable
    {
        protected ADOConnectorColumn() : this(string.Empty) {}

        public ADOConnectorColumn(string fieldname) : base(fieldname)
        {
        }
           
        public ADOConnectorColumn(ADODB.Field field) : this(field.Name)
        {
        }

        // -----------------------------------------
        #region // ISerializable
        protected ADOConnectorColumn(SerializationInfo info, StreamingContext
context) {}
        protected override void GetObjectData(SerializationInfo info,
StreamingContext context) {}
        #endregion

    }
}

TG.Data.DataColumn is a C++ managed abstract class. A derived class in the same
assembly as TG.Data.DataColumn works fine.

All the references are correct as far as I can see, and the entire project
builds with 0 errors and only 1 warning in the c++ class (LINK : warning
LNK4243: DLL containing objects compiled with /clr is not linked with /NOENTRY;
image may not run correctly). VS.net 2003/DX9 summer 2004 release/XPSP2.

Googling was no help.

Any suggestions?

TIA
Steve.