This subject is abundant if typed in Google, but I keep getting a mistake,

I have created a Form Called "Edit Aircraft". I want this form to be opened
by another form. I inserted the Sample code found in the help-file:

Private Sub Form_Open(Cancel As Integer)
   Dim intReturn As Integer
   intReturn = MsgBox("Do you want to configure your aircraft now?",
vbYesNo)
   Select Case intReturn
       Case vbYes
           ' Open Order Details form.
           DoCmd.OpenForm "Edit Aircraft"
       Case vbNo
           MsgBox "Remember to configure this aircraft at a later time"
           Cancel = True                    ' Cancel Open event.
   End Select
End Sub

This triggers a error when the form is being opened saying:

Procedure declaration does not match description event or procedure having
the same name.

I set the property for Form On Open [event procedure]

I don't understand what the problem is. I created a new Form "Form1" and
inserted the identical OnOpen event (with "Form1 offcourse", and it works as
advertised.

Anyone knows where the problem is?

Jacco

my complete code for "Edit Aircraft" is:

Option Compare Database
Private Sub Form_Open(Cancel As Integer)
   Dim intReturn As Integer
   intReturn = MsgBox("Enter order details now?", vbYesNo)
   Select Case intReturn
       Case vbYes
           ' Open Order Details form.
           DoCmd.OpenForm "Edit Aircraft"
       Case vbNo
           MsgBox "Remember to enter order details by 5 P.M."
           Cancel = True                    ' Cancel Open event.
   End Select
End Sub

Private Sub List28_BeforeUpdate()
   Dim rs As Object
   Set rs = Me.Recordset.Clone
   rs.FindFirst "[Type] = '" & Me![List28] & "'"
   If Not rs.EOF Then Me.Bookmark = rs.Bookmark
End Sub

Private Sub List28_AfterUpdate()
   Dim rs As Object
   Set rs = Me.Recordset.Clone
   rs.FindFirst "[Type] = '" & Me![List28] & "'"
   If Not rs.EOF Then Me.Bookmark = rs.Bookmark
End Sub

Private Sub addnewaircraft_Click()
On Error GoTo Err_addnewaircraft_Click

   DoCmd.GoToRecord , , acNewRec

Exit_addnewaircraft_Click:
   Exit Sub

Err_addnewaircraft_Click:
   MsgBox Err.Description
   Resume Exit_addnewaircraft_Click

End Sub

Private Sub deletecurrentaircraft_Click()
On Error GoTo Err_deletecurrentaircraft_Click

   DoCmd.DoMenuItem acFormBar, acEditMenu, 8, , acMenuVer70
   DoCmd.DoMenuItem acFormBar, acEditMenu, 6, , acMenuVer70

Exit_deletecurrentaircraft_Click:
   DoCmd.DoMenuItem acFormBar, acRecordsMenu, 5, , acMenuVer70
   Exit Sub

Err_deletecurrentaircraft_Click:
   MsgBox Err.Description
   Resume Exit_deletecurrentaircraft_Click

End Sub
Private Sub refreshaircraft_Click()
On Error GoTo Err_refreshaircraft_Click

   DoCmd.DoMenuItem acFormBar, acRecordsMenu, 5, , acMenuVer70

Exit_refreshaircraft_Click:
   Exit Sub

Err_refreshaircraft_Click:
   MsgBox Err.Description
   Resume Exit_refreshaircraft_Click

End Sub
Private Sub undochanges_Click()
On Error GoTo Err_undochanges_Click

   DoCmd.DoMenuItem acFormBar, acEditMenu, acUndo, , acMenuVer70
   DoCmd.DoMenuItem acFormBar, acRecordsMenu, 5, , acMenuVer70

Exit_undochanges_Click:
   Exit Sub

Err_undochanges_Click:
   MsgBox Err.Description
   Resume Exit_undochanges_Click

End Sub