title: Checking off pdf checkbox with itextsharp
body: <p>I've tried so many different ways, but I can't get the check box to be checked! Here's what I've tried:</p>
  
  <pre><code>var reader = new iTextSharp.text.pdf.PdfReader(originalFormLocation);
  using (var stamper = new iTextSharp.text.pdf.PdfStamper(reader,ms)) {
      var formFields = stamper.AcroFields;
      formFields.SetField("IsNo", "1");
      formFields.SetField("IsNo", "true");
      formFields.SetField("IsNo", "On");
  }
  </code></pre>
  
  <p>None of them work. Any ideas?</p>