title: Add and remove columns from a Tablix in rdlc report
body: <p>I want to create a report with dynamic number of columns.
  I have used the solutions of these two following links to load and modify my rdlc report file.</p>
  
  <ol>
  <li><a href="http://dobrzanski.net/2009/02/06/how-to-dynamically-add-new-columns-to-report-created-with-reporting-services/" rel="nofollow noreferrer">http://dobrzanski.net/2009/02/06/how-to-dynamically-add-new-columns-to-report-created-with-reporting-services/</a></li>
  <li><a href="https://stackoverflow.com/questions/310669/why-does-c-sharp-xmldocument-loadxmlstring-fail-when-an-xml-header-is-included">Why does C# XmlDocument.LoadXml(string) fail when an XML header is included?</a></li>
  </ol>
  
  <p>but the problem is that when i use the Save method of xmlDocument to save the report anything happens.</p>
  
  <p>what is my mistake???</p>