Problem w/.EnableCancelKey = xlErrorHandler
 

I am runing XL97 in Win95.

I am trying to prevent a user from disabling a userform using
Ctrl-Break. I know how to stop him from clicking on the X but he can
still press Ctrl-Break and get out from the code..
I am using the code below to trap Ctrl-Break error 18 but it doesn't
work and I can't figure out why.

No matter what I do I don't seem to get it to go to the ErrorHandler
while UserForm1 is showing.

Thanks for any help.

'This is in ThisWorkbook
Private Sub Workbook_Open()
Call On_Open
End Sub

'This is in Module1
Private Sub On_Open()
On Error GoTo ErrorHandler
Application.EnableCancelKey = xlErrorHandler
UserForm1.Show
ErrorHandler:
If Err.Number = 18 Then
UserForm1.Hide
MsgBox "pressed break"
End If
End Sub