[AccessD] Error 3265. Item not found in this collection?!!?

Hi group,
 
a user reported an error. The error message displayed the following info:
Source: DAO.Fields
Number: 3265
Description: Item not found in this collection
Call Stack: Switchdatabase.Message_Check_GAS.Check1015
                 Switchdatabase.Form_frm_GAS_GENERATE.cmdGenerate_Click
 
The line that causes the error is (see code below for details): 
rv = MsgBox("Duplicate value!! Delete original record?" & vbCr _
               , vbYesNo, "Answer question")
 
WHY does this occur?
The user is using Win NT. The error does NOT occur on Win2000. We never had this problem before, not on NT and not on Win2000.
 
Please advise!
 
TIA

Sander
 
This is the code that caused the problem:
 
Public Function Check_1015(msgtype As String) As String
   Dim Status As String
   Dim rs, rsb As Recordset
   Dim db As Database
   Dim teller, i As Long
   Dim rv As String
 
   On Error GoTo Check_1015_Error
 
   Status = "Ok"
   If msgtype = "I" Then
...
...
      Set rsb = db.OpenRecordset("Select * from V4_GAS_Bronbestand_Verhuizingen where connect_EAN = '" & rs!Connect_EAN & "'", dbReadOnly)
      If rsb.EOF = False Then
         rv = MsgBox("Duplicate value!! Delete original record?" & vbCr _
               , vbYesNo, "Answer question")
....
 
 
 

		
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