title: add filter to excel sheet
body: <p>I have a c# app that runs some code and produces a report in Excel. The report is fine - do all the formatting except for when I go to put the autofilter on.</p>
  
  <p>I get the error message "AutoFilter method of Range class failed". When I step through the code I can add a filter via VBA and it works - not sure why its not working from within my c# app.</p>
  
  <pre><code>using Excel = Microsoft.Office.Interop.Excel;
  
  Excel.Range rngFilter = _xlWorksheet.get_Range("A2", "L2");
  rngFilter.AutoFilter();
  rngFilter = null;
  </code></pre>