Prevent unwanted beforeUpdate event

[bdoodle]

Please advise:
I'm trying to avoid a BeforeUpdate event from being triggered as a result of actions in an InputBox (within the same BeforeUpdate procedure) I use to ask the user to confirm (or deny) the outrageous value just entered. If the user does confirm the value in the InputBox, everything works okay. If the user either hits the Cancel button in the InputBox or does not confirm the input value, the code works but triggers an immediate return to the BeforeUpdate procedure. (It issues the error msg in the beginning of the subroutine that I'm missing an input value.)

I'm using EnableEvents = False, but it isn't working. The problem is in my "validity check" and my code follows:

Private Sub txtFlexROM_BeforeUpdate(ByVal Cancel As MSForms.ReturnBoolean)

FlexROMIsInvalid = False
txtFlexRoundedROM = ""
txtFlexImp = ""

If chkFlexUnavail.Value = False Then
    If IsEmpty(txtFlexROM) = True Then
        MsgBox "You must enter a valid Flexion measurement or click unavailable.", vbOKOnly
        Exit Sub
    End If
    If IsNumeric(txtFlexROM) = False Then
        MsgBox "You must enter a valid Flexion measurement number or click unavailable.", vbOKOnly
        Exit Sub
    End If
    
Application.EnableEvents = False

    ' test for validity
    If (Round(txtFlexROM / 10, 0) * 10) < -40 Or _
        (Round(txtFlexROM / 10, 0) * 10) > 220 Then
        
            vConfirmInput = ""
            On Error GoTo Canceled
            vConfirmInput = Application.InputBox _
                (Prompt:="This Flexion measurement is invalid. " _
                & "Hit Cancel to enter a different value. To confirm it, please re-enter it and hit Okay.", _
                Title:="Cancel or Confirm Flexion measurement", Type:=1)

            If IsEmpty(vConfirmInput) = False And IsNumeric(vConfirmInput) And _
                vConfirmInput - txtFlexROM = 0 Then
                    FlexROMIsInvalid = True
                    txtFlexROM.ForeColor = &H8000000D
                    Application.EnableEvents = True
                    Exit Sub
            Else
                    txtFlexROM = ""
                    chkFlexUnavail.SetFocus
                    txtFlexROM.SetFocus
                Application.EnableEvents = True
                Exit Sub
            End If
        
    End If
    
Other code follows...

Canceled:
Application.EnableEvents = True

End Sub

Thanks for any help!