Private Sub btn_Click()

    Dim ̵ As Boolean
    Dim ù As Range

    Select Case MultiPage1.Value
    
        Case 0
        
            If Dir(txt.Value) <> "" Then ̵ = True
        
        Case 1
        
            On Error Resume Next
        
                Set ù = Range(ref.Value)
                
                If Err.Number = 0 Then ̵ = True
                
            On Error GoTo 0
        
    End Select

    If ̵ = True Then MultiPage1.Value = MultiPage1.Value + 1

End Sub