title: Erratic behaviour with InStrRev when supplying start position
body: <p>I don't understand the results of any of the below. I understand InStrRev gives position of last 'matches' (right-to-left) &amp; can comprehend the result when I don't give a start position. No matter if the start begins at left or right, 1 or 2 should give something other than 0.</p>
  
  <pre><code>Private Sub Form_Load()
  Dim TestString As String
  TestString = "ABCDEFGHCIJK"
  msgbox = InStrRev(TestString, "C", 1) 'produces 0 if optional start parameter is 1 or 2
  msgbox = InStrRev(TestString, "C", 3) 'produces 3 if start parameter is 3-8
  msgbox = InStrRev(TestString, "C", 9) 'produces 9 if start parameter is 9-12
  '13+ produces 0 as expected since its length of string is only 12
  End Sub
  </code></pre>
  
  <p>Microsoft documentation on function: <a href="http://office.microsoft.com/en-us/access-help/instrrev-function-HA001228858.aspx" rel="nofollow">access</a> &amp; <a href="http://msdn.microsoft.com/en-us/library/t2ekk41a%28v=vs.80%29.aspx" rel="nofollow">visual studio</a>. On the visual studio page I tried the example at the bottom of the page &amp; got same result, so I know its working. However my brain isn't getting. I also understand the InStr function with &amp; without a start position</p>