I am getting an error when trying to use an ADODB.Recordset that was passed
from a VB6 application to a VB.Net class library using COM Interop. I am
running this on WinXP SP2 using the .Net Framework 1.1 and MDAC 2.8 SP1.

This is what I've done:
- I compiled the VB.Net DLL and registered it so it can be used in the VB6
app using "regasm /tlb:VBNETClass.tlb VBNETClass.dll".
- From the VB6 app, I added a reference to the VB.Net DLL.
- I added references to the ADO 2.8 Library from both the VB6 app and the
VB.Net library. (I also tried ADO 2.6 and 2.7 later but they had the same
results.)
- I built the VB6 EXE and copied it to the directory containing the VB.Net
DLL.

When I run the VB6 EXE, all of the message boxes appear fine except for the
one on the last line of PrintRecordCount below. Instead, I get the following
error:

- - - -
Run-time error '-2147467262 (80004002)';
QueryInterface for interface ADODB._Recordset failed.
- - - -
(The debugger shows it to be a System.InvalidCastException.)

Any ideas?

VB6 APP

Private Sub Command1_Click()

   Dim ccw As New VBNETClass.Class1

   Dim rs As New ADODB.Recordset
   Set rs = CreateObject("ADODB.Recordset")
   rs.CursorType = adOpenStatic
   rs.CursorLocation = adUseClient
   rs.Fields.Append "FieldName1", adVarChar, 10
   rs.Fields.Append "FieldName2", adInteger
   rs.Open

   rs.AddNew
   rs("FieldName1") = "David"
   rs("FieldName2") = 17
   rs.Update

   rs.Sort = "FieldName2"
   rs.MoveFirst

   MsgBox ("In VB6 App, about to call VB.Net class...")
' this line works
   MsgBox ("In VB6 Class, rs.RecordCount = " & rs.RecordCount)

   ccw.PrintRecordCount (rs)
   
End Sub

VB.NET CLASS LIBRARY (VBNETClass)

Public Class Class1
   Public Function PrintRecordCount(ByVal rs As ADODB.Recordset)

       MsgBox("In VB.Net Class, about to display RecordCount... ")
' this line produces the error
       MsgBox("In VB.Net Class, rs.RecordCount = " & rs.RecordCount)

   End Function
End Class

(I also tried changing the type of the input parameter to
ADODB.RecordsetClass and ADODB._Recordset but the same error resulted.)