title: Excel VBA -> Last date/time save + automatically update
body: <p>I have excel document and sheet name: Overview</p>
  
  <p>Because a lot of people modify this workbook, I want to add in B1 cell user ID (computer name) + date/time (so person who last modify sheet and date &amp; time when this was happened)</p>
  
  <p>I open macro tool (alt+F11) -> I use this for first time:</p>
  
  <p><strong>1. create new module and add code:</strong></p>
  
  <pre><code>Function LastSaveDate()
   Application.Volatile True
   LastSaveDate = FileDateTime(ThisWorkbook.FullName)  
  End Function
  </code></pre>
  
  <p><strong>2. click on left side inside of Macro... "Thisworkbook" and add following code:</strong></p>
  
  <blockquote>
  <pre><code>Private Sub Workbook_Open()
  MsgBox Date
  Worksheets("Overview").Range("B1").Value = Date
  End Sub
  </code></pre>
  </blockquote>
  
  <p>What I'm doing wrong, excel in B1 cell showing "12.11.2013 18:35:14"  (I use in this cell: =LastSaveDate()       ) also showing right date and time, but when I save (as enabled macro document) it and reopen there is just showing ""12.11.2013  0:00:00" and there is no code in this cell B1.</p>