itextsharp setting background opacity not working
<p>I have the following code to set background color to one of my fields but for some reason I can not control the transparency of the background. Can someone please take a look at it and let me know what I am doing wrong. Thanks.</p>

<pre><code> using (var newFileStream = new FileStream(fileNameNew, FileMode.Create))
        {
            // Open existing PDF
            var pdfReader = new PdfReader(existingFileStream);

            // PdfStamper, which will create
            var stamper = new PdfStamper(pdfReader, newFileStream);

            var form = stamper.AcroFields;
            var fieldKeys = form.Fields.Keys;


            foreach (string fieldKey in fieldKeys)
            {
                if (fieldKey.Equals("Title"))
                {
                    form.SetFieldProperty(fieldKey, "bgcolor", new BaseColor(System.Drawing.Color.FromArgb(20,225,160,0)),null);
                    form.SetField(fieldKey, "Test");

                }
                else
                {
                    form.SetField(fieldKey, "REPLACED!");
                }
            }
            stamper.FormFlattening = true;
            stamper.Close();
            pdfReader.Close();
        }
</code></pre>