title: string.Replace (or other string modification) not working
body: <p>For the following code, I can't get the <code>string.Replace</code> to work:</p>
  
  <pre><code>someTestString.Replace(someID.ToString(), sessionID);
  </code></pre>
  
  <p>when I debug and check parameters they have values I expect - i.e. <code>someID.ToString()</code> got "1087163075", and <code>sessionID</code> has "108716308" and <code>someTestString</code> contains "1087163075".</p>
  
  <p><strong>I have no idea why this would not work change <code>someTestString</code></strong></p>
  
  <p>Complete sample:</p>
  
  <pre><code>string someTestString = 
        "&lt;a href='myfoldert/108716305-1.jpg' target='_blank'&gt;108716305-1.jpg&lt;/a&gt;"
  someTestString.Replace("108716305", "NewId42");  
  </code></pre>
  
  <p>the result (in <code>someTestString</code>) should be this:</p>
  
  <pre><code>"&lt;a href='myfoldert/NewId42-1.jpg' target='_blank'&gt;NewId42-1.jpg&lt;/a&gt;" 
  </code></pre>
  
  <p>but it doesn't change.  The string for <code>someTestString</code> remains unchanged after hitting my code.</p>